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third-party-mirror/openjdk/jdk25u/HEAD/./src/hotspot/share/services/heapDumper.cpp
blob: 731a26f7cf1ed17973cccee39e1855b07b952858 [file]
/*
* Copyright (c) 2005, 2025, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2023, Alibaba Group Holding Limited. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#include "classfile/classLoaderData.inline.hpp"
#include "classfile/classLoaderDataGraph.hpp"
#include "classfile/javaClasses.inline.hpp"
#include "classfile/symbolTable.hpp"
#include "classfile/vmClasses.hpp"
#include "classfile/vmSymbols.hpp"
#include "gc/shared/gcLocker.hpp"
#include "gc/shared/gcVMOperations.hpp"
#include "gc/shared/workerThread.hpp"
#include "jfr/jfrEvents.hpp"
#include "jvm.h"
#include "memory/allocation.inline.hpp"
#include "memory/resourceArea.hpp"
#include "memory/universe.hpp"
#include "oops/fieldStreams.inline.hpp"
#include "oops/klass.inline.hpp"
#include "oops/objArrayKlass.hpp"
#include "oops/objArrayOop.inline.hpp"
#include "oops/oop.inline.hpp"
#include "oops/typeArrayOop.inline.hpp"
#include "runtime/arguments.hpp"
#include "runtime/continuationWrapper.inline.hpp"
#include "runtime/frame.inline.hpp"
#include "runtime/handles.inline.hpp"
#include "runtime/javaCalls.hpp"
#include "runtime/javaThread.inline.hpp"
#include "runtime/jniHandles.hpp"
#include "runtime/os.hpp"
#include "runtime/threads.hpp"
#include "runtime/threadSMR.hpp"
#include "runtime/vframe.hpp"
#include "runtime/vmOperations.hpp"
#include "runtime/vmThread.hpp"
#include "runtime/timerTrace.hpp"
#include "services/heapDumper.hpp"
#include "services/heapDumperCompression.hpp"
#include "services/threadService.hpp"
#include "utilities/checkedCast.hpp"
#include "utilities/macros.hpp"
#include "utilities/ostream.hpp"
#ifdef LINUX
#include "os_linux.hpp"
#endif
/*
* HPROF binary format - description copied from:
* src/share/demo/jvmti/hprof/hprof_io.c
*
*
* header "JAVA PROFILE 1.0.2" (0-terminated)
*
* u4 size of identifiers. Identifiers are used to represent
* UTF8 strings, objects, stack traces, etc. They usually
* have the same size as host pointers.
* u4 high word
* u4 low word number of milliseconds since 0:00 GMT, 1/1/70
* [record]* a sequence of records.
*
*
* Record format:
*
* u1 a TAG denoting the type of the record
* u4 number of *microseconds* since the time stamp in the
* header. (wraps around in a little more than an hour)
* u4 number of bytes *remaining* in the record. Note that
* this number excludes the tag and the length field itself.
* [u1]* BODY of the record (a sequence of bytes)
*
*
* The following TAGs are supported:
*
* TAG BODY notes
*----------------------------------------------------------
* HPROF_UTF8 a UTF8-encoded name
*
* id name ID
* [u1]* UTF8 characters (no trailing zero)
*
* HPROF_LOAD_CLASS a newly loaded class
*
* u4 class serial number (> 0)
* id class object ID
* u4 stack trace serial number
* id class name ID
*
* HPROF_UNLOAD_CLASS an unloading class
*
* u4 class serial_number
*
* HPROF_FRAME a Java stack frame
*
* id stack frame ID
* id method name ID
* id method signature ID
* id source file name ID
* u4 class serial number
* i4 line number. >0: normal
* -1: unknown
* -2: compiled method
* -3: native method
*
* HPROF_TRACE a Java stack trace
*
* u4 stack trace serial number
* u4 thread serial number
* u4 number of frames
* [id]* stack frame IDs
*
*
* HPROF_ALLOC_SITES a set of heap allocation sites, obtained after GC
*
* u2 flags 0x0001: incremental vs. complete
* 0x0002: sorted by allocation vs. live
* 0x0004: whether to force a GC
* u4 cutoff ratio
* u4 total live bytes
* u4 total live instances
* u8 total bytes allocated
* u8 total instances allocated
* u4 number of sites that follow
* [u1 is_array: 0: normal object
* 2: object array
* 4: boolean array
* 5: char array
* 6: float array
* 7: double array
* 8: byte array
* 9: short array
* 10: int array
* 11: long array
* u4 class serial number (may be zero during startup)
* u4 stack trace serial number
* u4 number of bytes alive
* u4 number of instances alive
* u4 number of bytes allocated
* u4]* number of instance allocated
*
* HPROF_START_THREAD a newly started thread.
*
* u4 thread serial number (> 0)
* id thread object ID
* u4 stack trace serial number
* id thread name ID
* id thread group name ID
* id thread group parent name ID
*
* HPROF_END_THREAD a terminating thread.
*
* u4 thread serial number
*
* HPROF_HEAP_SUMMARY heap summary
*
* u4 total live bytes
* u4 total live instances
* u8 total bytes allocated
* u8 total instances allocated
*
* HPROF_HEAP_DUMP denote a heap dump
*
* [heap dump sub-records]*
*
* There are four kinds of heap dump sub-records:
*
* u1 sub-record type
*
* HPROF_GC_ROOT_UNKNOWN unknown root
*
* id object ID
*
* HPROF_GC_ROOT_THREAD_OBJ thread object
*
* id thread object ID (may be 0 for a
* thread newly attached through JNI)
* u4 thread sequence number
* u4 stack trace sequence number
*
* HPROF_GC_ROOT_JNI_GLOBAL JNI global ref root
*
* id object ID
* id JNI global ref ID
*
* HPROF_GC_ROOT_JNI_LOCAL JNI local ref
*
* id object ID
* u4 thread serial number
* u4 frame # in stack trace (-1 for empty)
*
* HPROF_GC_ROOT_JAVA_FRAME Java stack frame
*
* id object ID
* u4 thread serial number
* u4 frame # in stack trace (-1 for empty)
*
* HPROF_GC_ROOT_NATIVE_STACK Native stack
*
* id object ID
* u4 thread serial number
*
* HPROF_GC_ROOT_STICKY_CLASS System class
*
* id object ID
*
* HPROF_GC_ROOT_THREAD_BLOCK Reference from thread block
*
* id object ID
* u4 thread serial number
*
* HPROF_GC_ROOT_MONITOR_USED Busy monitor
*
* id object ID
*
* HPROF_GC_CLASS_DUMP dump of a class object
*
* id class object ID
* u4 stack trace serial number
* id super class object ID
* id class loader object ID
* id signers object ID
* id protection domain object ID
* id reserved
* id reserved
*
* u4 instance size (in bytes)
*
* u2 size of constant pool
* [u2, constant pool index,
* ty, type
* 2: object
* 4: boolean
* 5: char
* 6: float
* 7: double
* 8: byte
* 9: short
* 10: int
* 11: long
* vl]* and value
*
* u2 number of static fields
* [id, static field name,
* ty, type,
* vl]* and value
*
* u2 number of inst. fields (not inc. super)
* [id, instance field name,
* ty]* type
*
* HPROF_GC_INSTANCE_DUMP dump of a normal object
*
* id object ID
* u4 stack trace serial number
* id class object ID
* u4 number of bytes that follow
* [vl]* instance field values (class, followed
* by super, super's super ...)
*
* HPROF_GC_OBJ_ARRAY_DUMP dump of an object array
*
* id array object ID
* u4 stack trace serial number
* u4 number of elements
* id array class ID
* [id]* elements
*
* HPROF_GC_PRIM_ARRAY_DUMP dump of a primitive array
*
* id array object ID
* u4 stack trace serial number
* u4 number of elements
* u1 element type
* 4: boolean array
* 5: char array
* 6: float array
* 7: double array
* 8: byte array
* 9: short array
* 10: int array
* 11: long array
* [u1]* elements
*
* HPROF_CPU_SAMPLES a set of sample traces of running threads
*
* u4 total number of samples
* u4 # of traces
* [u4 # of samples
* u4]* stack trace serial number
*
* HPROF_CONTROL_SETTINGS the settings of on/off switches
*
* u4 0x00000001: alloc traces on/off
* 0x00000002: cpu sampling on/off
* u2 stack trace depth
*
*
* When the header is "JAVA PROFILE 1.0.2" a heap dump can optionally
* be generated as a sequence of heap dump segments. This sequence is
* terminated by an end record. The additional tags allowed by format
* "JAVA PROFILE 1.0.2" are:
*
* HPROF_HEAP_DUMP_SEGMENT denote a heap dump segment
*
* [heap dump sub-records]*
* The same sub-record types allowed by HPROF_HEAP_DUMP
*
* HPROF_HEAP_DUMP_END denotes the end of a heap dump
*
*/
// HPROF tags
enum hprofTag : u1 {
// top-level records
HPROF_UTF8 = 0x01,
HPROF_LOAD_CLASS = 0x02,
HPROF_UNLOAD_CLASS = 0x03,
HPROF_FRAME = 0x04,
HPROF_TRACE = 0x05,
HPROF_ALLOC_SITES = 0x06,
HPROF_HEAP_SUMMARY = 0x07,
HPROF_START_THREAD = 0x0A,
HPROF_END_THREAD = 0x0B,
HPROF_HEAP_DUMP = 0x0C,
HPROF_CPU_SAMPLES = 0x0D,
HPROF_CONTROL_SETTINGS = 0x0E,
// 1.0.2 record types
HPROF_HEAP_DUMP_SEGMENT = 0x1C,
HPROF_HEAP_DUMP_END = 0x2C,
// field types
HPROF_ARRAY_OBJECT = 0x01,
HPROF_NORMAL_OBJECT = 0x02,
HPROF_BOOLEAN = 0x04,
HPROF_CHAR = 0x05,
HPROF_FLOAT = 0x06,
HPROF_DOUBLE = 0x07,
HPROF_BYTE = 0x08,
HPROF_SHORT = 0x09,
HPROF_INT = 0x0A,
HPROF_LONG = 0x0B,
// data-dump sub-records
HPROF_GC_ROOT_UNKNOWN = 0xFF,
HPROF_GC_ROOT_JNI_GLOBAL = 0x01,
HPROF_GC_ROOT_JNI_LOCAL = 0x02,
HPROF_GC_ROOT_JAVA_FRAME = 0x03,
HPROF_GC_ROOT_NATIVE_STACK = 0x04,
HPROF_GC_ROOT_STICKY_CLASS = 0x05,
HPROF_GC_ROOT_THREAD_BLOCK = 0x06,
HPROF_GC_ROOT_MONITOR_USED = 0x07,
HPROF_GC_ROOT_THREAD_OBJ = 0x08,
HPROF_GC_CLASS_DUMP = 0x20,
HPROF_GC_INSTANCE_DUMP = 0x21,
HPROF_GC_OBJ_ARRAY_DUMP = 0x22,
HPROF_GC_PRIM_ARRAY_DUMP = 0x23
};
// Default stack trace ID (used for dummy HPROF_TRACE record)
enum {
STACK_TRACE_ID = 1,
INITIAL_CLASS_COUNT = 200
};
// Supports I/O operations for a dump
// Base class for dump and parallel dump
class AbstractDumpWriter : public CHeapObj<mtInternal> {
protected:
enum {
io_buffer_max_size = 1*M,
dump_segment_header_size = 9
};
char* _buffer; // internal buffer
size_t _size;
size_t _pos;
bool _in_dump_segment; // Are we currently in a dump segment?
bool _is_huge_sub_record; // Are we writing a sub-record larger than the buffer size?
DEBUG_ONLY(size_t _sub_record_left;) // The bytes not written for the current sub-record.
DEBUG_ONLY(bool _sub_record_ended;) // True if we have called the end_sub_record().
char* buffer() const { return _buffer; }
size_t buffer_size() const { return _size; }
void set_position(size_t pos) { _pos = pos; }
// Can be called if we have enough room in the buffer.
void write_fast(const void* s, size_t len);
// Returns true if we have enough room in the buffer for 'len' bytes.
bool can_write_fast(size_t len);
void write_address(address a);
public:
AbstractDumpWriter() :
_buffer(nullptr),
_size(io_buffer_max_size),
_pos(0),
_in_dump_segment(false) { }
// Total number of bytes written to the disk
virtual julong bytes_written() const = 0;
// Return non-null if error occurred
virtual char const* error() const = 0;
size_t position() const { return _pos; }
// writer functions
virtual void write_raw(const void* s, size_t len);
void write_u1(u1 x);
void write_u2(u2 x);
void write_u4(u4 x);
void write_u8(u8 x);
void write_objectID(oop o);
void write_rootID(oop* p);
void write_symbolID(Symbol* o);
void write_classID(Klass* k);
void write_id(u4 x);
// Start a new sub-record. Starts a new heap dump segment if needed.
void start_sub_record(u1 tag, u4 len);
// Ends the current sub-record.
void end_sub_record();
// Finishes the current dump segment if not already finished.
void finish_dump_segment();
// Flush internal buffer to persistent storage
virtual void flush() = 0;
};
void AbstractDumpWriter::write_fast(const void* s, size_t len) {
assert(!_in_dump_segment || (_sub_record_left >= len), "sub-record too large");
assert(buffer_size() - position() >= len, "Must fit");
DEBUG_ONLY(_sub_record_left -= len);
memcpy(buffer() + position(), s, len);
set_position(position() + len);
}
bool AbstractDumpWriter::can_write_fast(size_t len) {
return buffer_size() - position() >= len;
}
// write raw bytes
void AbstractDumpWriter::write_raw(const void* s, size_t len) {
assert(!_in_dump_segment || (_sub_record_left >= len), "sub-record too large");
DEBUG_ONLY(_sub_record_left -= len);
// flush buffer to make room.
while (len > buffer_size() - position()) {
assert(!_in_dump_segment || _is_huge_sub_record,
"Cannot overflow in non-huge sub-record.");
size_t to_write = buffer_size() - position();
memcpy(buffer() + position(), s, to_write);
s = (void*) ((char*) s + to_write);
len -= to_write;
set_position(position() + to_write);
flush();
}
memcpy(buffer() + position(), s, len);
set_position(position() + len);
}
// Makes sure we inline the fast write into the write_u* functions. This is a big speedup.
#define WRITE_KNOWN_TYPE(p, len) do { if (can_write_fast((len))) write_fast((p), (len)); \
else write_raw((p), (len)); } while (0)
void AbstractDumpWriter::write_u1(u1 x) {
WRITE_KNOWN_TYPE(&x, 1);
}
void AbstractDumpWriter::write_u2(u2 x) {
u2 v;
Bytes::put_Java_u2((address)&v, x);
WRITE_KNOWN_TYPE(&v, 2);
}
void AbstractDumpWriter::write_u4(u4 x) {
u4 v;
Bytes::put_Java_u4((address)&v, x);
WRITE_KNOWN_TYPE(&v, 4);
}
void AbstractDumpWriter::write_u8(u8 x) {
u8 v;
Bytes::put_Java_u8((address)&v, x);
WRITE_KNOWN_TYPE(&v, 8);
}
void AbstractDumpWriter::write_address(address a) {
#ifdef _LP64
write_u8((u8)a);
#else
write_u4((u4)a);
#endif
}
void AbstractDumpWriter::write_objectID(oop o) {
write_address(cast_from_oop<address>(o));
}
void AbstractDumpWriter::write_rootID(oop* p) {
write_address((address)p);
}
void AbstractDumpWriter::write_symbolID(Symbol* s) {
write_address((address)((uintptr_t)s));
}
void AbstractDumpWriter::write_id(u4 x) {
#ifdef _LP64
write_u8((u8) x);
#else
write_u4(x);
#endif
}
// We use java mirror as the class ID
void AbstractDumpWriter::write_classID(Klass* k) {
write_objectID(k->java_mirror());
}
void AbstractDumpWriter::finish_dump_segment() {
if (_in_dump_segment) {
assert(_sub_record_left == 0, "Last sub-record not written completely");
assert(_sub_record_ended, "sub-record must have ended");
// Fix up the dump segment length if we haven't written a huge sub-record last
// (in which case the segment length was already set to the correct value initially).
if (!_is_huge_sub_record) {
assert(position() > dump_segment_header_size, "Dump segment should have some content");
Bytes::put_Java_u4((address) (buffer() + 5),
(u4) (position() - dump_segment_header_size));
} else {
// Finish process huge sub record
// Set _is_huge_sub_record to false so the parallel dump writer can flush data to file.
_is_huge_sub_record = false;
}
_in_dump_segment = false;
flush();
}
}
void AbstractDumpWriter::start_sub_record(u1 tag, u4 len) {
if (!_in_dump_segment) {
if (position() > 0) {
flush();
}
assert(position() == 0 && buffer_size() > dump_segment_header_size, "Must be at the start");
write_u1(HPROF_HEAP_DUMP_SEGMENT);
write_u4(0); // timestamp
// Will be fixed up later if we add more sub-records. If this is a huge sub-record,
// this is already the correct length, since we don't add more sub-records.
write_u4(len);
assert(Bytes::get_Java_u4((address)(buffer() + 5)) == len, "Inconsistent size!");
_in_dump_segment = true;
_is_huge_sub_record = len > buffer_size() - dump_segment_header_size;
} else if (_is_huge_sub_record || (len > buffer_size() - position())) {
// This object will not fit in completely or the last sub-record was huge.
// Finish the current segment and try again.
finish_dump_segment();
start_sub_record(tag, len);
return;
}
DEBUG_ONLY(_sub_record_left = len);
DEBUG_ONLY(_sub_record_ended = false);
write_u1(tag);
}
void AbstractDumpWriter::end_sub_record() {
assert(_in_dump_segment, "must be in dump segment");
assert(_sub_record_left == 0, "sub-record not written completely");
assert(!_sub_record_ended, "Must not have ended yet");
DEBUG_ONLY(_sub_record_ended = true);
}
// Supports I/O operations for a dump
class DumpWriter : public AbstractDumpWriter {
private:
FileWriter* _writer;
AbstractCompressor* _compressor;
size_t _bytes_written;
char* _error;
// Compression support
char* _out_buffer;
size_t _out_size;
size_t _out_pos;
char* _tmp_buffer;
size_t _tmp_size;
private:
void do_compress();
public:
DumpWriter(const char* path, bool overwrite, AbstractCompressor* compressor);
~DumpWriter();
julong bytes_written() const override { return (julong) _bytes_written; }
char const* error() const override { return _error; }
void set_error(const char* error) { _error = (char*)error; }
bool has_error() const { return _error != nullptr; }
const char* get_file_path() const { return _writer->get_file_path(); }
AbstractCompressor* compressor() { return _compressor; }
bool is_overwrite() const { return _writer->is_overwrite(); }
void flush() override;
private:
// internals for DumpMerger
friend class DumpMerger;
void set_bytes_written(julong bytes_written) { _bytes_written = bytes_written; }
int get_fd() const { return _writer->get_fd(); }
void set_compressor(AbstractCompressor* p) { _compressor = p; }
};
DumpWriter::DumpWriter(const char* path, bool overwrite, AbstractCompressor* compressor) :
AbstractDumpWriter(),
_writer(new (std::nothrow) FileWriter(path, overwrite)),
_compressor(compressor),
_bytes_written(0),
_error(nullptr),
_out_buffer(nullptr),
_out_size(0),
_out_pos(0),
_tmp_buffer(nullptr),
_tmp_size(0) {
_error = (char*)_writer->open_writer();
if (_error == nullptr) {
_buffer = (char*)os::malloc(io_buffer_max_size, mtInternal);
if (compressor != nullptr) {
_error = (char*)_compressor->init(io_buffer_max_size, &_out_size, &_tmp_size);
if (_error == nullptr) {
if (_out_size > 0) {
_out_buffer = (char*)os::malloc(_out_size, mtInternal);
}
if (_tmp_size > 0) {
_tmp_buffer = (char*)os::malloc(_tmp_size, mtInternal);
}
}
}
}
// initialize internal buffer
_pos = 0;
_size = io_buffer_max_size;
}
DumpWriter::~DumpWriter(){
if (_buffer != nullptr) {
os::free(_buffer);
}
if (_out_buffer != nullptr) {
os::free(_out_buffer);
}
if (_tmp_buffer != nullptr) {
os::free(_tmp_buffer);
}
if (_writer != nullptr) {
delete _writer;
}
_bytes_written = -1;
}
// flush any buffered bytes to the file
void DumpWriter::flush() {
if (_pos <= 0) {
return;
}
if (has_error()) {
_pos = 0;
return;
}
char* result = nullptr;
if (_compressor == nullptr) {
result = (char*)_writer->write_buf(_buffer, _pos);
_bytes_written += _pos;
} else {
do_compress();
if (!has_error()) {
result = (char*)_writer->write_buf(_out_buffer, _out_pos);
_bytes_written += _out_pos;
}
}
_pos = 0; // reset pos to make internal buffer available
if (result != nullptr) {
set_error(result);
}
}
void DumpWriter::do_compress() {
const char* msg = _compressor->compress(_buffer, _pos, _out_buffer, _out_size,
_tmp_buffer, _tmp_size, &_out_pos);
if (msg != nullptr) {
set_error(msg);
}
}
class DumperClassCacheTable;
class DumperClassCacheTableEntry;
// Support class with a collection of functions used when dumping the heap
class DumperSupport : AllStatic {
public:
// write a header of the given type
static void write_header(AbstractDumpWriter* writer, hprofTag tag, u4 len);
// returns hprof tag for the given type signature
static hprofTag sig2tag(Symbol* sig);
// returns hprof tag for the given basic type
static hprofTag type2tag(BasicType type);
// Returns the size of the data to write.
static u4 sig2size(Symbol* sig);
// returns the size of the instance of the given class
static u4 instance_size(InstanceKlass* ik, DumperClassCacheTableEntry* class_cache_entry = nullptr);
// dump a jfloat
static void dump_float(AbstractDumpWriter* writer, jfloat f);
// dump a jdouble
static void dump_double(AbstractDumpWriter* writer, jdouble d);
// dumps the raw value of the given field
static void dump_field_value(AbstractDumpWriter* writer, char type, oop obj, int offset);
// returns the size of the static fields; also counts the static fields
static u4 get_static_fields_size(InstanceKlass* ik, u2& field_count);
// dumps static fields of the given class
static void dump_static_fields(AbstractDumpWriter* writer, Klass* k);
// dump the raw values of the instance fields of the given object
static void dump_instance_fields(AbstractDumpWriter* writer, oop o, DumperClassCacheTableEntry* class_cache_entry);
// get the count of the instance fields for a given class
static u2 get_instance_fields_count(InstanceKlass* ik);
// dumps the definition of the instance fields for a given class
static void dump_instance_field_descriptors(AbstractDumpWriter* writer, Klass* k);
// creates HPROF_GC_INSTANCE_DUMP record for the given object
static void dump_instance(AbstractDumpWriter* writer, oop o, DumperClassCacheTable* class_cache);
// creates HPROF_GC_CLASS_DUMP record for the given instance class
static void dump_instance_class(AbstractDumpWriter* writer, Klass* k);
// creates HPROF_GC_CLASS_DUMP record for a given array class
static void dump_array_class(AbstractDumpWriter* writer, Klass* k);
// creates HPROF_GC_OBJ_ARRAY_DUMP record for the given object array
static void dump_object_array(AbstractDumpWriter* writer, objArrayOop array);
// creates HPROF_GC_PRIM_ARRAY_DUMP record for the given type array
static void dump_prim_array(AbstractDumpWriter* writer, typeArrayOop array);
// create HPROF_FRAME record for the given method and bci
static void dump_stack_frame(AbstractDumpWriter* writer, int frame_serial_num, int class_serial_num, Method* m, int bci);
// check if we need to truncate an array
static int calculate_array_max_length(AbstractDumpWriter* writer, arrayOop array, short header_size);
// fixes up the current dump record and writes HPROF_HEAP_DUMP_END record
static void end_of_dump(AbstractDumpWriter* writer);
static oop mask_dormant_archived_object(oop o, oop ref_obj) {
if (o != nullptr && o->klass()->java_mirror_no_keepalive() == nullptr) {
// Ignore this object since the corresponding java mirror is not loaded.
// Might be a dormant archive object.
report_dormant_archived_object(o, ref_obj);
return nullptr;
} else {
return o;
}
}
static void report_dormant_archived_object(oop o, oop ref_obj) {
if (log_is_enabled(Trace, aot, heap)) {
ResourceMark rm;
if (ref_obj != nullptr) {
log_trace(aot, heap)("skipped dormant archived object " INTPTR_FORMAT " (%s) referenced by " INTPTR_FORMAT " (%s)",
p2i(o), o->klass()->external_name(),
p2i(ref_obj), ref_obj->klass()->external_name());
} else {
log_trace(aot, heap)("skipped dormant archived object " INTPTR_FORMAT " (%s)",
p2i(o), o->klass()->external_name());
}
}
}
};
// Hash table of klasses to the klass metadata. This should greatly improve the
// hash dumping performance. This hash table is supposed to be used by a single
// thread only.
//
class DumperClassCacheTableEntry : public CHeapObj<mtServiceability> {
friend class DumperClassCacheTable;
private:
GrowableArray<char> _sigs_start;
GrowableArray<int> _offsets;
u4 _instance_size;
int _entries;
public:
DumperClassCacheTableEntry() : _instance_size(0), _entries(0) {};
int field_count() { return _entries; }
char sig_start(int field_idx) { return _sigs_start.at(field_idx); }
int offset(int field_idx) { return _offsets.at(field_idx); }
u4 instance_size() { return _instance_size; }
};
class DumperClassCacheTable {
private:
// ResourceHashtable SIZE is specified at compile time so we
// use 1031 which is the first prime after 1024.
static constexpr size_t TABLE_SIZE = 1031;
// Maintain the cache for N classes. This limits memory footprint
// impact, regardless of how many classes we have in the dump.
// This also improves look up performance by keeping the statically
// sized table from overloading.
static constexpr int CACHE_TOP = 256;
typedef ResourceHashtable<InstanceKlass*, DumperClassCacheTableEntry*,
TABLE_SIZE, AnyObj::C_HEAP, mtServiceability> PtrTable;
PtrTable* _ptrs;
// Single-slot cache to handle the major case of objects of the same
// class back-to-back, e.g. from T[].
InstanceKlass* _last_ik;
DumperClassCacheTableEntry* _last_entry;
void unlink_all(PtrTable* table) {
class CleanupEntry: StackObj {
public:
bool do_entry(InstanceKlass*& key, DumperClassCacheTableEntry*& entry) {
delete entry;
return true;
}
} cleanup;
table->unlink(&cleanup);
}
public:
DumperClassCacheTableEntry* lookup_or_create(InstanceKlass* ik) {
if (_last_ik == ik) {
return _last_entry;
}
DumperClassCacheTableEntry* entry;
DumperClassCacheTableEntry** from_cache = _ptrs->get(ik);
if (from_cache == nullptr) {
entry = new DumperClassCacheTableEntry();
for (HierarchicalFieldStream<JavaFieldStream> fld(ik); !fld.done(); fld.next()) {
if (!fld.access_flags().is_static()) {
Symbol* sig = fld.signature();
entry->_sigs_start.push(sig->char_at(0));
entry->_offsets.push(fld.offset());
entry->_entries++;
entry->_instance_size += DumperSupport::sig2size(sig);
}
}
if (_ptrs->number_of_entries() >= CACHE_TOP) {
// We do not track the individual hit rates for table entries.
// Purge the entire table, and let the cache catch up with new
// distribution.
unlink_all(_ptrs);
}
_ptrs->put(ik, entry);
} else {
entry = *from_cache;
}
// Remember for single-slot cache.
_last_ik = ik;
_last_entry = entry;
return entry;
}
DumperClassCacheTable() : _ptrs(new (mtServiceability) PtrTable), _last_ik(nullptr), _last_entry(nullptr) {}
~DumperClassCacheTable() {
unlink_all(_ptrs);
delete _ptrs;
}
};
// write a header of the given type
void DumperSupport:: write_header(AbstractDumpWriter* writer, hprofTag tag, u4 len) {
writer->write_u1(tag);
writer->write_u4(0); // current ticks
writer->write_u4(len);
}
// returns hprof tag for the given type signature
hprofTag DumperSupport::sig2tag(Symbol* sig) {
switch (sig->char_at(0)) {
case JVM_SIGNATURE_CLASS : return HPROF_NORMAL_OBJECT;
case JVM_SIGNATURE_ARRAY : return HPROF_NORMAL_OBJECT;
case JVM_SIGNATURE_BYTE : return HPROF_BYTE;
case JVM_SIGNATURE_CHAR : return HPROF_CHAR;
case JVM_SIGNATURE_FLOAT : return HPROF_FLOAT;
case JVM_SIGNATURE_DOUBLE : return HPROF_DOUBLE;
case JVM_SIGNATURE_INT : return HPROF_INT;
case JVM_SIGNATURE_LONG : return HPROF_LONG;
case JVM_SIGNATURE_SHORT : return HPROF_SHORT;
case JVM_SIGNATURE_BOOLEAN : return HPROF_BOOLEAN;
default : ShouldNotReachHere(); /* to shut up compiler */ return HPROF_BYTE;
}
}
hprofTag DumperSupport::type2tag(BasicType type) {
switch (type) {
case T_BYTE : return HPROF_BYTE;
case T_CHAR : return HPROF_CHAR;
case T_FLOAT : return HPROF_FLOAT;
case T_DOUBLE : return HPROF_DOUBLE;
case T_INT : return HPROF_INT;
case T_LONG : return HPROF_LONG;
case T_SHORT : return HPROF_SHORT;
case T_BOOLEAN : return HPROF_BOOLEAN;
default : ShouldNotReachHere(); /* to shut up compiler */ return HPROF_BYTE;
}
}
u4 DumperSupport::sig2size(Symbol* sig) {
switch (sig->char_at(0)) {
case JVM_SIGNATURE_CLASS:
case JVM_SIGNATURE_ARRAY: return sizeof(address);
case JVM_SIGNATURE_BOOLEAN:
case JVM_SIGNATURE_BYTE: return 1;
case JVM_SIGNATURE_SHORT:
case JVM_SIGNATURE_CHAR: return 2;
case JVM_SIGNATURE_INT:
case JVM_SIGNATURE_FLOAT: return 4;
case JVM_SIGNATURE_LONG:
case JVM_SIGNATURE_DOUBLE: return 8;
default: ShouldNotReachHere(); /* to shut up compiler */ return 0;
}
}
template<typename T, typename F> T bit_cast(F from) { // replace with the real thing when we can use c++20
T to;
static_assert(sizeof(to) == sizeof(from), "must be of the same size");
memcpy(&to, &from, sizeof(to));
return to;
}
// dump a jfloat
void DumperSupport::dump_float(AbstractDumpWriter* writer, jfloat f) {
if (g_isnan(f)) {
writer->write_u4(0x7fc00000); // collapsing NaNs
} else {
writer->write_u4(bit_cast<u4>(f));
}
}
// dump a jdouble
void DumperSupport::dump_double(AbstractDumpWriter* writer, jdouble d) {
if (g_isnan(d)) {
writer->write_u8(0x7ff80000ull << 32); // collapsing NaNs
} else {
writer->write_u8(bit_cast<u8>(d));
}
}
// dumps the raw value of the given field
void DumperSupport::dump_field_value(AbstractDumpWriter* writer, char type, oop obj, int offset) {
switch (type) {
case JVM_SIGNATURE_CLASS :
case JVM_SIGNATURE_ARRAY : {
oop o = obj->obj_field_access<ON_UNKNOWN_OOP_REF | AS_NO_KEEPALIVE>(offset);
o = mask_dormant_archived_object(o, obj);
assert(oopDesc::is_oop_or_null(o), "Expected an oop or nullptr at " PTR_FORMAT, p2i(o));
writer->write_objectID(o);
break;
}
case JVM_SIGNATURE_BYTE : {
jbyte b = obj->byte_field(offset);
writer->write_u1(b);
break;
}
case JVM_SIGNATURE_CHAR : {
jchar c = obj->char_field(offset);
writer->write_u2(c);
break;
}
case JVM_SIGNATURE_SHORT : {
jshort s = obj->short_field(offset);
writer->write_u2(s);
break;
}
case JVM_SIGNATURE_FLOAT : {
jfloat f = obj->float_field(offset);
dump_float(writer, f);
break;
}
case JVM_SIGNATURE_DOUBLE : {
jdouble d = obj->double_field(offset);
dump_double(writer, d);
break;
}
case JVM_SIGNATURE_INT : {
jint i = obj->int_field(offset);
writer->write_u4(i);
break;
}
case JVM_SIGNATURE_LONG : {
jlong l = obj->long_field(offset);
writer->write_u8(l);
break;
}
case JVM_SIGNATURE_BOOLEAN : {
jboolean b = obj->bool_field(offset);
writer->write_u1(b);
break;
}
default : {
ShouldNotReachHere();
break;
}
}
}
// returns the size of the instance of the given class
u4 DumperSupport::instance_size(InstanceKlass* ik, DumperClassCacheTableEntry* class_cache_entry) {
if (class_cache_entry != nullptr) {
return class_cache_entry->instance_size();
} else {
u4 size = 0;
for (HierarchicalFieldStream<JavaFieldStream> fld(ik); !fld.done(); fld.next()) {
if (!fld.access_flags().is_static()) {
size += sig2size(fld.signature());
}
}
return size;
}
}
u4 DumperSupport::get_static_fields_size(InstanceKlass* ik, u2& field_count) {
field_count = 0;
u4 size = 0;
for (JavaFieldStream fldc(ik); !fldc.done(); fldc.next()) {
if (fldc.access_flags().is_static()) {
field_count++;
size += sig2size(fldc.signature());
}
}
// Add in resolved_references which is referenced by the cpCache
// The resolved_references is an array per InstanceKlass holding the
// strings and other oops resolved from the constant pool.
oop resolved_references = ik->constants()->resolved_references_or_null();
if (resolved_references != nullptr) {
field_count++;
size += sizeof(address);
// Add in the resolved_references of the used previous versions of the class
// in the case of RedefineClasses
InstanceKlass* prev = ik->previous_versions();
while (prev != nullptr && prev->constants()->resolved_references_or_null() != nullptr) {
field_count++;
size += sizeof(address);
prev = prev->previous_versions();
}
}
// Also provide a pointer to the init_lock if present, so there aren't unreferenced int[0]
// arrays.
oop init_lock = ik->init_lock();
if (init_lock != nullptr) {
field_count++;
size += sizeof(address);
}
// We write the value itself plus a name and a one byte type tag per field.
return checked_cast<u4>(size + field_count * (sizeof(address) + 1));
}
// dumps static fields of the given class
void DumperSupport::dump_static_fields(AbstractDumpWriter* writer, Klass* k) {
InstanceKlass* ik = InstanceKlass::cast(k);
// dump the field descriptors and raw values
for (JavaFieldStream fld(ik); !fld.done(); fld.next()) {
if (fld.access_flags().is_static()) {
Symbol* sig = fld.signature();
writer->write_symbolID(fld.name()); // name
writer->write_u1(sig2tag(sig)); // type
// value
dump_field_value(writer, sig->char_at(0), ik->java_mirror(), fld.offset());
}
}
// Add resolved_references for each class that has them
oop resolved_references = ik->constants()->resolved_references_or_null();
if (resolved_references != nullptr) {
writer->write_symbolID(vmSymbols::resolved_references_name()); // name
writer->write_u1(sig2tag(vmSymbols::object_array_signature())); // type
writer->write_objectID(resolved_references);
// Also write any previous versions
InstanceKlass* prev = ik->previous_versions();
while (prev != nullptr && prev->constants()->resolved_references_or_null() != nullptr) {
writer->write_symbolID(vmSymbols::resolved_references_name()); // name
writer->write_u1(sig2tag(vmSymbols::object_array_signature())); // type
writer->write_objectID(prev->constants()->resolved_references());
prev = prev->previous_versions();
}
}
// Add init lock to the end if the class is not yet initialized
oop init_lock = ik->init_lock();
if (init_lock != nullptr) {
writer->write_symbolID(vmSymbols::init_lock_name()); // name
writer->write_u1(sig2tag(vmSymbols::int_array_signature())); // type
writer->write_objectID(init_lock);
}
}
// dump the raw values of the instance fields of the given object
void DumperSupport::dump_instance_fields(AbstractDumpWriter* writer, oop o, DumperClassCacheTableEntry* class_cache_entry) {
assert(class_cache_entry != nullptr, "Pre-condition: must be provided");
for (int idx = 0; idx < class_cache_entry->field_count(); idx++) {
dump_field_value(writer, class_cache_entry->sig_start(idx), o, class_cache_entry->offset(idx));
}
}
// dumps the definition of the instance fields for a given class
u2 DumperSupport::get_instance_fields_count(InstanceKlass* ik) {
u2 field_count = 0;
for (JavaFieldStream fldc(ik); !fldc.done(); fldc.next()) {
if (!fldc.access_flags().is_static()) field_count++;
}
return field_count;
}
// dumps the definition of the instance fields for a given class
void DumperSupport::dump_instance_field_descriptors(AbstractDumpWriter* writer, Klass* k) {
InstanceKlass* ik = InstanceKlass::cast(k);
// dump the field descriptors
for (JavaFieldStream fld(ik); !fld.done(); fld.next()) {
if (!fld.access_flags().is_static()) {
Symbol* sig = fld.signature();
writer->write_symbolID(fld.name()); // name
writer->write_u1(sig2tag(sig)); // type
}
}
}
// creates HPROF_GC_INSTANCE_DUMP record for the given object
void DumperSupport::dump_instance(AbstractDumpWriter* writer, oop o, DumperClassCacheTable* class_cache) {
InstanceKlass* ik = InstanceKlass::cast(o->klass());
DumperClassCacheTableEntry* cache_entry = class_cache->lookup_or_create(ik);
u4 is = instance_size(ik, cache_entry);
u4 size = 1 + sizeof(address) + 4 + sizeof(address) + 4 + is;
writer->start_sub_record(HPROF_GC_INSTANCE_DUMP, size);
writer->write_objectID(o);
writer->write_u4(STACK_TRACE_ID);
// class ID
writer->write_classID(ik);
// number of bytes that follow
writer->write_u4(is);
// field values
dump_instance_fields(writer, o, cache_entry);
writer->end_sub_record();
}
// creates HPROF_GC_CLASS_DUMP record for the given instance class
void DumperSupport::dump_instance_class(AbstractDumpWriter* writer, Klass* k) {
InstanceKlass* ik = InstanceKlass::cast(k);
// We can safepoint and do a heap dump at a point where we have a Klass,
// but no java mirror class has been setup for it. So we need to check
// that the class is at least loaded, to avoid crash from a null mirror.
if (!ik->is_loaded()) {
return;
}
u2 static_fields_count = 0;
u4 static_size = get_static_fields_size(ik, static_fields_count);
u2 instance_fields_count = get_instance_fields_count(ik);
u4 instance_fields_size = instance_fields_count * (sizeof(address) + 1);
u4 size = checked_cast<u4>(1 + sizeof(address) + 4 + 6 * sizeof(address) + 4 + 2 + 2 + static_size + 2 + instance_fields_size);
writer->start_sub_record(HPROF_GC_CLASS_DUMP, size);
// class ID
writer->write_classID(ik);
writer->write_u4(STACK_TRACE_ID);
// super class ID
InstanceKlass* java_super = ik->java_super();
if (java_super == nullptr) {
writer->write_objectID(oop(nullptr));
} else {
writer->write_classID(java_super);
}
writer->write_objectID(ik->class_loader());
writer->write_objectID(ik->signers());
writer->write_objectID(ik->protection_domain());
// reserved
writer->write_objectID(oop(nullptr));
writer->write_objectID(oop(nullptr));
// instance size
writer->write_u4(DumperSupport::instance_size(ik));
// size of constant pool - ignored by HAT 1.1
writer->write_u2(0);
// static fields
writer->write_u2(static_fields_count);
dump_static_fields(writer, ik);
// description of instance fields
writer->write_u2(instance_fields_count);
dump_instance_field_descriptors(writer, ik);
writer->end_sub_record();
}
// creates HPROF_GC_CLASS_DUMP record for the given array class
void DumperSupport::dump_array_class(AbstractDumpWriter* writer, Klass* k) {
InstanceKlass* ik = nullptr; // bottom class for object arrays, null for primitive type arrays
if (k->is_objArray_klass()) {
Klass *bk = ObjArrayKlass::cast(k)->bottom_klass();
assert(bk != nullptr, "checking");
if (bk->is_instance_klass()) {
ik = InstanceKlass::cast(bk);
}
}
u4 size = 1 + sizeof(address) + 4 + 6 * sizeof(address) + 4 + 2 + 2 + 2;
writer->start_sub_record(HPROF_GC_CLASS_DUMP, size);
writer->write_classID(k);
writer->write_u4(STACK_TRACE_ID);
// super class of array classes is java.lang.Object
InstanceKlass* java_super = k->java_super();
assert(java_super != nullptr, "checking");
writer->write_classID(java_super);
writer->write_objectID(ik == nullptr ? oop(nullptr) : ik->class_loader());
writer->write_objectID(ik == nullptr ? oop(nullptr) : ik->signers());
writer->write_objectID(ik == nullptr ? oop(nullptr) : ik->protection_domain());
writer->write_objectID(oop(nullptr)); // reserved
writer->write_objectID(oop(nullptr));
writer->write_u4(0); // instance size
writer->write_u2(0); // constant pool
writer->write_u2(0); // static fields
writer->write_u2(0); // instance fields
writer->end_sub_record();
}
// Hprof uses an u4 as record length field,
// which means we need to truncate arrays that are too long.
int DumperSupport::calculate_array_max_length(AbstractDumpWriter* writer, arrayOop array, short header_size) {
BasicType type = ArrayKlass::cast(array->klass())->element_type();
assert(type >= T_BOOLEAN && type <= T_OBJECT, "invalid array element type");
int length = array->length();
int type_size;
if (type == T_OBJECT) {
type_size = sizeof(address);
} else {
type_size = type2aelembytes(type);
}
size_t length_in_bytes = (size_t)length * type_size;
uint max_bytes = max_juint - header_size;
if (length_in_bytes > max_bytes) {
length = max_bytes / type_size;
length_in_bytes = (size_t)length * type_size;
warning("cannot dump array of type %s[] with length %d; truncating to length %d",
type2name_tab[type], array->length(), length);
}
return length;
}
// creates HPROF_GC_OBJ_ARRAY_DUMP record for the given object array
void DumperSupport::dump_object_array(AbstractDumpWriter* writer, objArrayOop array) {
// sizeof(u1) + 2 * sizeof(u4) + sizeof(objectID) + sizeof(classID)
short header_size = 1 + 2 * 4 + 2 * sizeof(address);
int length = calculate_array_max_length(writer, array, header_size);
u4 size = checked_cast<u4>(header_size + length * sizeof(address));
writer->start_sub_record(HPROF_GC_OBJ_ARRAY_DUMP, size);
writer->write_objectID(array);
writer->write_u4(STACK_TRACE_ID);
writer->write_u4(length);
// array class ID
writer->write_classID(array->klass());
// [id]* elements
for (int index = 0; index < length; index++) {
oop o = array->obj_at(index);
o = mask_dormant_archived_object(o, array);
writer->write_objectID(o);
}
writer->end_sub_record();
}
#define WRITE_ARRAY(Array, Type, Size, Length) \
for (int i = 0; i < Length; i++) { writer->write_##Size((Size)Array->Type##_at(i)); }
// creates HPROF_GC_PRIM_ARRAY_DUMP record for the given type array
void DumperSupport::dump_prim_array(AbstractDumpWriter* writer, typeArrayOop array) {
BasicType type = TypeArrayKlass::cast(array->klass())->element_type();
// 2 * sizeof(u1) + 2 * sizeof(u4) + sizeof(objectID)
short header_size = 2 * 1 + 2 * 4 + sizeof(address);
int length = calculate_array_max_length(writer, array, header_size);
int type_size = type2aelembytes(type);
u4 length_in_bytes = (u4)length * type_size;
u4 size = header_size + length_in_bytes;
writer->start_sub_record(HPROF_GC_PRIM_ARRAY_DUMP, size);
writer->write_objectID(array);
writer->write_u4(STACK_TRACE_ID);
writer->write_u4(length);
writer->write_u1(type2tag(type));
// nothing to copy
if (length == 0) {
writer->end_sub_record();
return;
}
// If the byte ordering is big endian then we can copy most types directly
switch (type) {
case T_INT : {
if (Endian::is_Java_byte_ordering_different()) {
WRITE_ARRAY(array, int, u4, length);
} else {
writer->write_raw(array->int_at_addr(0), length_in_bytes);
}
break;
}
case T_BYTE : {
writer->write_raw(array->byte_at_addr(0), length_in_bytes);
break;
}
case T_CHAR : {
if (Endian::is_Java_byte_ordering_different()) {
WRITE_ARRAY(array, char, u2, length);
} else {
writer->write_raw(array->char_at_addr(0), length_in_bytes);
}
break;
}
case T_SHORT : {
if (Endian::is_Java_byte_ordering_different()) {
WRITE_ARRAY(array, short, u2, length);
} else {
writer->write_raw(array->short_at_addr(0), length_in_bytes);
}
break;
}
case T_BOOLEAN : {
if (Endian::is_Java_byte_ordering_different()) {
WRITE_ARRAY(array, bool, u1, length);
} else {
writer->write_raw(array->bool_at_addr(0), length_in_bytes);
}
break;
}
case T_LONG : {
if (Endian::is_Java_byte_ordering_different()) {
WRITE_ARRAY(array, long, u8, length);
} else {
writer->write_raw(array->long_at_addr(0), length_in_bytes);
}
break;
}
// handle float/doubles in a special value to ensure than NaNs are
// written correctly. TO DO: Check if we can avoid this on processors that
// use IEEE 754.
case T_FLOAT : {
for (int i = 0; i < length; i++) {
dump_float(writer, array->float_at(i));
}
break;
}
case T_DOUBLE : {
for (int i = 0; i < length; i++) {
dump_double(writer, array->double_at(i));
}
break;
}
default : ShouldNotReachHere();
}
writer->end_sub_record();
}
// create a HPROF_FRAME record of the given Method* and bci
void DumperSupport::dump_stack_frame(AbstractDumpWriter* writer,
int frame_serial_num,
int class_serial_num,
Method* m,
int bci) {
int line_number;
if (m->is_native()) {
line_number = -3; // native frame
} else {
line_number = m->line_number_from_bci(bci);
}
write_header(writer, HPROF_FRAME, 4*oopSize + 2*sizeof(u4));
writer->write_id(frame_serial_num); // frame serial number
writer->write_symbolID(m->name()); // method's name
writer->write_symbolID(m->signature()); // method's signature
assert(m->method_holder()->is_instance_klass(), "not InstanceKlass");
writer->write_symbolID(m->method_holder()->source_file_name()); // source file name
writer->write_u4(class_serial_num); // class serial number
writer->write_u4((u4) line_number); // line number
}
// Support class used to generate HPROF_UTF8 records from the entries in the
// SymbolTable.
class SymbolTableDumper : public SymbolClosure {
private:
AbstractDumpWriter* _writer;
AbstractDumpWriter* writer() const { return _writer; }
public:
SymbolTableDumper(AbstractDumpWriter* writer) { _writer = writer; }
void do_symbol(Symbol** p);
};
void SymbolTableDumper::do_symbol(Symbol** p) {
ResourceMark rm;
Symbol* sym = *p;
int len = sym->utf8_length();
if (len > 0) {
char* s = sym->as_utf8();
DumperSupport::write_header(writer(), HPROF_UTF8, oopSize + len);
writer()->write_symbolID(sym);
writer()->write_raw(s, len);
}
}
// Support class used to generate HPROF_GC_CLASS_DUMP records
class ClassDumper : public KlassClosure {
private:
AbstractDumpWriter* _writer;
AbstractDumpWriter* writer() const { return _writer; }
public:
ClassDumper(AbstractDumpWriter* writer) : _writer(writer) {}
void do_klass(Klass* k) {
if (k->is_instance_klass()) {
DumperSupport::dump_instance_class(writer(), k);
} else {
DumperSupport::dump_array_class(writer(), k);
}
}
};
// Support class used to generate HPROF_LOAD_CLASS records
class LoadedClassDumper : public LockedClassesDo {
private:
AbstractDumpWriter* _writer;
GrowableArray<Klass*>* _klass_map;
u4 _class_serial_num;
AbstractDumpWriter* writer() const { return _writer; }
void add_class_serial_number(Klass* k, int serial_num) {
_klass_map->at_put_grow(serial_num, k);
}
public:
LoadedClassDumper(AbstractDumpWriter* writer, GrowableArray<Klass*>* klass_map)
: _writer(writer), _klass_map(klass_map), _class_serial_num(0) {}
void do_klass(Klass* k) {
// len of HPROF_LOAD_CLASS record
u4 remaining = 2 * oopSize + 2 * sizeof(u4);
DumperSupport::write_header(writer(), HPROF_LOAD_CLASS, remaining);
// class serial number is just a number
writer()->write_u4(++_class_serial_num);
// class ID
writer()->write_classID(k);
// add the Klass* and class serial number pair
add_class_serial_number(k, _class_serial_num);
writer()->write_u4(STACK_TRACE_ID);
// class name ID
Symbol* name = k->name();
writer()->write_symbolID(name);
}
};
// Support class used to generate HPROF_GC_ROOT_JNI_LOCAL records
class JNILocalsDumper : public OopClosure {
private:
AbstractDumpWriter* _writer;
u4 _thread_serial_num;
int _frame_num;
AbstractDumpWriter* writer() const { return _writer; }
public:
JNILocalsDumper(AbstractDumpWriter* writer, u4 thread_serial_num) {
_writer = writer;
_thread_serial_num = thread_serial_num;
_frame_num = -1; // default - empty stack
}
void set_frame_number(int n) { _frame_num = n; }
void do_oop(oop* obj_p);
void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); }
};
void JNILocalsDumper::do_oop(oop* obj_p) {
// ignore null handles
oop o = *obj_p;
if (o != nullptr) {
u4 size = 1 + sizeof(address) + 4 + 4;
writer()->start_sub_record(HPROF_GC_ROOT_JNI_LOCAL, size);
writer()->write_objectID(o);
writer()->write_u4(_thread_serial_num);
writer()->write_u4((u4)_frame_num);
writer()->end_sub_record();
}
}
// Support class used to generate HPROF_GC_ROOT_JNI_GLOBAL records
class JNIGlobalsDumper : public OopClosure {
private:
AbstractDumpWriter* _writer;
AbstractDumpWriter* writer() const { return _writer; }
public:
JNIGlobalsDumper(AbstractDumpWriter* writer) {
_writer = writer;
}
void do_oop(oop* obj_p);
void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); }
};
void JNIGlobalsDumper::do_oop(oop* obj_p) {
oop o = NativeAccess<AS_NO_KEEPALIVE>::oop_load(obj_p);
// ignore these
if (o == nullptr) return;
// we ignore global ref to symbols and other internal objects
if (o->is_instance() || o->is_objArray() || o->is_typeArray()) {
u4 size = 1 + 2 * sizeof(address);
writer()->start_sub_record(HPROF_GC_ROOT_JNI_GLOBAL, size);
writer()->write_objectID(o);
writer()->write_rootID(obj_p); // global ref ID
writer()->end_sub_record();
}
};
// Support class used to generate HPROF_GC_ROOT_STICKY_CLASS records
class StickyClassDumper : public KlassClosure {
private:
AbstractDumpWriter* _writer;
AbstractDumpWriter* writer() const { return _writer; }
public:
StickyClassDumper(AbstractDumpWriter* writer) {
_writer = writer;
}
void do_klass(Klass* k) {
if (k->is_instance_klass()) {
InstanceKlass* ik = InstanceKlass::cast(k);
u4 size = 1 + sizeof(address);
writer()->start_sub_record(HPROF_GC_ROOT_STICKY_CLASS, size);
writer()->write_classID(ik);
writer()->end_sub_record();
}
}
};
// Support class used to generate HPROF_GC_ROOT_JAVA_FRAME records.
class JavaStackRefDumper : public StackObj {
private:
AbstractDumpWriter* _writer;
u4 _thread_serial_num;
int _frame_num;
AbstractDumpWriter* writer() const { return _writer; }
public:
JavaStackRefDumper(AbstractDumpWriter* writer, u4 thread_serial_num)
: _writer(writer), _thread_serial_num(thread_serial_num), _frame_num(-1) // default - empty stack
{
}
void set_frame_number(int n) { _frame_num = n; }
void dump_java_stack_refs(StackValueCollection* values);
};
void JavaStackRefDumper::dump_java_stack_refs(StackValueCollection* values) {
for (int index = 0; index < values->size(); index++) {
if (values->at(index)->type() == T_OBJECT) {
oop o = values->obj_at(index)();
if (o != nullptr) {
u4 size = 1 + sizeof(address) + 4 + 4;
writer()->start_sub_record(HPROF_GC_ROOT_JAVA_FRAME, size);
writer()->write_objectID(o);
writer()->write_u4(_thread_serial_num);
writer()->write_u4((u4)_frame_num);
writer()->end_sub_record();
}
}
}
}
// Class to collect, store and dump thread-related data:
// - HPROF_TRACE and HPROF_FRAME records;
// - HPROF_GC_ROOT_THREAD_OBJ/HPROF_GC_ROOT_JAVA_FRAME/HPROF_GC_ROOT_JNI_LOCAL subrecords.
class ThreadDumper : public CHeapObj<mtInternal> {
public:
enum class ThreadType { Platform, MountedVirtual, UnmountedVirtual };
private:
ThreadType _thread_type;
JavaThread* _java_thread;
oop _thread_oop;
GrowableArray<StackFrameInfo*>* _frames;
// non-null if the thread is OOM thread
Method* _oome_constructor;
int _thread_serial_num;
int _start_frame_serial_num;
vframe* get_top_frame() const;
public:
static bool should_dump_pthread(JavaThread* thread) {
return thread->threadObj() != nullptr && !thread->is_exiting() && !thread->is_hidden_from_external_view();
}
static bool should_dump_vthread(oop vt) {
return java_lang_VirtualThread::state(vt) != java_lang_VirtualThread::NEW
&& java_lang_VirtualThread::state(vt) != java_lang_VirtualThread::TERMINATED;
}
static bool is_vthread_mounted(oop vt) {
// The code should be consistent with the "mounted virtual thread" case
// (VM_HeapDumper::dump_stack_traces(), ThreadDumper::get_top_frame()).
// I.e. virtual thread is mounted if its carrierThread is not null
// and is_vthread_mounted() for the carrier thread returns true.
oop carrier_thread = java_lang_VirtualThread::carrier_thread(vt);
if (carrier_thread == nullptr) {
return false;
}
JavaThread* java_thread = java_lang_Thread::thread(carrier_thread);
return java_thread->is_vthread_mounted();
}
ThreadDumper(ThreadType thread_type, JavaThread* java_thread, oop thread_oop);
~ThreadDumper() {
for (int index = 0; index < _frames->length(); index++) {
delete _frames->at(index);
}
delete _frames;
}
// affects frame_count
void add_oom_frame(Method* oome_constructor) {
assert(_start_frame_serial_num == 0, "add_oom_frame cannot be called after init_serial_nums");
_oome_constructor = oome_constructor;
}
void init_serial_nums(volatile int* thread_counter, volatile int* frame_counter) {
assert(_start_frame_serial_num == 0, "already initialized");
_thread_serial_num = Atomic::fetch_then_add(thread_counter, 1);
_start_frame_serial_num = Atomic::fetch_then_add(frame_counter, frame_count());
}
bool oom_thread() const {
return _oome_constructor != nullptr;
}
int frame_count() const {
return _frames->length() + (oom_thread() ? 1 : 0);
}
u4 thread_serial_num() const {
return (u4)_thread_serial_num;
}
u4 stack_trace_serial_num() const {
return (u4)(_thread_serial_num + STACK_TRACE_ID);
}
// writes HPROF_TRACE and HPROF_FRAME records
// returns number of dumped frames
void dump_stack_traces(AbstractDumpWriter* writer, GrowableArray<Klass*>* klass_map);
// writes HPROF_GC_ROOT_THREAD_OBJ subrecord
void dump_thread_obj(AbstractDumpWriter* writer);
// Walk the stack of the thread.
// Dumps a HPROF_GC_ROOT_JAVA_FRAME subrecord for each local
// Dumps a HPROF_GC_ROOT_JNI_LOCAL subrecord for each JNI local
void dump_stack_refs(AbstractDumpWriter* writer);
};
ThreadDumper::ThreadDumper(ThreadType thread_type, JavaThread* java_thread, oop thread_oop)
: _thread_type(thread_type), _java_thread(java_thread), _thread_oop(thread_oop),
_oome_constructor(nullptr),
_thread_serial_num(0), _start_frame_serial_num(0)
{
// sanity checks
if (_thread_type == ThreadType::UnmountedVirtual) {
assert(_java_thread == nullptr, "sanity");
assert(_thread_oop != nullptr, "sanity");
} else {
assert(_java_thread != nullptr, "sanity");
assert(_thread_oop != nullptr, "sanity");
}
_frames = new (mtServiceability) GrowableArray<StackFrameInfo*>(10, mtServiceability);
bool stop_at_vthread_entry = _thread_type == ThreadType::MountedVirtual;
// vframes are resource allocated
Thread* current_thread = Thread::current();
ResourceMark rm(current_thread);
HandleMark hm(current_thread);
for (vframe* vf = get_top_frame(); vf != nullptr; vf = vf->sender()) {
if (stop_at_vthread_entry && vf->is_vthread_entry()) {
break;
}
if (vf->is_java_frame()) {
javaVFrame* jvf = javaVFrame::cast(vf);
_frames->append(new StackFrameInfo(jvf, false));
} else {
// ignore non-Java frames
}
}
}
void ThreadDumper::dump_stack_traces(AbstractDumpWriter* writer, GrowableArray<Klass*>* klass_map) {
assert(_thread_serial_num != 0 && _start_frame_serial_num != 0, "serial_nums are not initialized");
// write HPROF_FRAME records for this thread's stack trace
int depth = _frames->length();
int frame_serial_num = _start_frame_serial_num;
if (oom_thread()) {
// OOM thread
// write fake frame that makes it look like the thread, which caused OOME,
// is in the OutOfMemoryError zero-parameter constructor
int oome_serial_num = klass_map->find(_oome_constructor->method_holder());
// the class serial number starts from 1
assert(oome_serial_num > 0, "OutOfMemoryError class not found");
DumperSupport::dump_stack_frame(writer, ++frame_serial_num, oome_serial_num, _oome_constructor, 0);
depth++;
}
for (int j = 0; j < _frames->length(); j++) {
StackFrameInfo* frame = _frames->at(j);
Method* m = frame->method();
int class_serial_num = klass_map->find(m->method_holder());
// the class serial number starts from 1
assert(class_serial_num > 0, "class not found");
DumperSupport::dump_stack_frame(writer, ++frame_serial_num, class_serial_num, m, frame->bci());
}
// write HPROF_TRACE record for the thread
DumperSupport::write_header(writer, HPROF_TRACE, checked_cast<u4>(3 * sizeof(u4) + depth * oopSize));
writer->write_u4(stack_trace_serial_num()); // stack trace serial number
writer->write_u4(thread_serial_num()); // thread serial number
writer->write_u4((u4)depth); // frame count (including oom frame)
for (int j = 1; j <= depth; j++) {
writer->write_id(_start_frame_serial_num + j);
}
}
void ThreadDumper::dump_thread_obj(AbstractDumpWriter * writer) {
assert(_thread_serial_num != 0 && _start_frame_serial_num != 0, "serial_num is not initialized");
u4 size = 1 + sizeof(address) + 4 + 4;
writer->start_sub_record(HPROF_GC_ROOT_THREAD_OBJ, size);
writer->write_objectID(_thread_oop);
writer->write_u4(thread_serial_num()); // thread serial number
writer->write_u4(stack_trace_serial_num()); // stack trace serial number
writer->end_sub_record();
}
void ThreadDumper::dump_stack_refs(AbstractDumpWriter * writer) {
assert(_thread_serial_num != 0 && _start_frame_serial_num != 0, "serial_num is not initialized");
JNILocalsDumper blk(writer, thread_serial_num());
if (_thread_type == ThreadType::Platform) {
if (!_java_thread->has_last_Java_frame()) {
// no last java frame but there may be JNI locals
_java_thread->active_handles()->oops_do(&blk);
return;
}
}
JavaStackRefDumper java_ref_dumper(writer, thread_serial_num());
// vframes are resource allocated
Thread* current_thread = Thread::current();
ResourceMark rm(current_thread);
HandleMark hm(current_thread);
bool stopAtVthreadEntry = _thread_type == ThreadType::MountedVirtual;
frame* last_entry_frame = nullptr;
bool is_top_frame = true;
int depth = 0;
if (oom_thread()) {
depth++;
}
for (vframe* vf = get_top_frame(); vf != nullptr; vf = vf->sender()) {
if (stopAtVthreadEntry && vf->is_vthread_entry()) {
break;
}
if (vf->is_java_frame()) {
javaVFrame* jvf = javaVFrame::cast(vf);
if (!(jvf->method()->is_native())) {
java_ref_dumper.set_frame_number(depth);
java_ref_dumper.dump_java_stack_refs(jvf->locals());
java_ref_dumper.dump_java_stack_refs(jvf->expressions());
} else {
// native frame
blk.set_frame_number(depth);
if (is_top_frame) {
// JNI locals for the top frame if mounted
assert(_java_thread != nullptr || jvf->method()->is_synchronized()
|| jvf->method()->is_object_wait0(), "impossible for unmounted vthread");
if (_java_thread != nullptr) {
_java_thread->active_handles()->oops_do(&blk);
}
} else {
if (last_entry_frame != nullptr) {
// JNI locals for the entry frame
assert(last_entry_frame->is_entry_frame(), "checking");
last_entry_frame->entry_frame_call_wrapper()->handles()->oops_do(&blk);
}
}
}
last_entry_frame = nullptr;
// increment only for Java frames
depth++;
} else {
// externalVFrame - for an entry frame then we report the JNI locals
// when we find the corresponding javaVFrame
frame* fr = vf->frame_pointer();
assert(fr != nullptr, "sanity check");
if (fr->is_entry_frame()) {
last_entry_frame = fr;
}
}
is_top_frame = false;
}
assert(depth == frame_count(), "total number of Java frames not matched");
}
vframe* ThreadDumper::get_top_frame() const {
if (_thread_type == ThreadType::UnmountedVirtual) {
ContinuationWrapper cont(java_lang_VirtualThread::continuation(_thread_oop));
if (cont.is_empty()) {
return nullptr;
}
assert(!cont.is_mounted(), "sanity check");
stackChunkOop chunk = cont.last_nonempty_chunk();
if (chunk == nullptr || chunk->is_empty()) {
return nullptr;
}
RegisterMap reg_map(cont.continuation(), RegisterMap::UpdateMap::include);
frame fr = chunk->top_frame(&reg_map);
vframe* vf = vframe::new_vframe(&fr, &reg_map, nullptr); // don't need JavaThread
return vf;
}
RegisterMap reg_map(_java_thread,
RegisterMap::UpdateMap::include,
RegisterMap::ProcessFrames::include,
RegisterMap::WalkContinuation::skip);
switch (_thread_type) {
case ThreadType::Platform:
if (!_java_thread->has_last_Java_frame()) {
return nullptr;
}
return _java_thread->is_vthread_mounted()
? _java_thread->carrier_last_java_vframe(&reg_map)
: _java_thread->platform_thread_last_java_vframe(&reg_map);
case ThreadType::MountedVirtual:
return _java_thread->last_java_vframe(&reg_map);
default: // make compilers happy
break;
}
ShouldNotReachHere();
return nullptr;
}
// Callback to dump thread-related data for unmounted virtual threads;
// implemented by VM_HeapDumper.
class UnmountedVThreadDumper {
public:
virtual void dump_vthread(oop vt, AbstractDumpWriter* segment_writer) = 0;
};
// Support class used when iterating over the heap.
class HeapObjectDumper : public ObjectClosure {
private:
AbstractDumpWriter* _writer;
AbstractDumpWriter* writer() { return _writer; }
UnmountedVThreadDumper* _vthread_dumper;
DumperClassCacheTable _class_cache;
public:
HeapObjectDumper(AbstractDumpWriter* writer, UnmountedVThreadDumper* vthread_dumper)
: _writer(writer), _vthread_dumper(vthread_dumper) {}
// called for each object in the heap
void do_object(oop o);
};
void HeapObjectDumper::do_object(oop o) {
// skip classes as these emitted as HPROF_GC_CLASS_DUMP records
if (o->klass() == vmClasses::Class_klass()) {
if (!java_lang_Class::is_primitive(o)) {
return;
}
}
if (DumperSupport::mask_dormant_archived_object(o, nullptr) == nullptr) {
return;
}
if (o->is_instance()) {
// create a HPROF_GC_INSTANCE record for each object
DumperSupport::dump_instance(writer(), o, &_class_cache);
// If we encounter an unmounted virtual thread it needs to be dumped explicitly
// (mounted virtual threads are dumped with their carriers).
if (java_lang_VirtualThread::is_instance(o)
&& ThreadDumper::should_dump_vthread(o) && !ThreadDumper::is_vthread_mounted(o)) {
_vthread_dumper->dump_vthread(o, writer());
}
} else if (o->is_objArray()) {
// create a HPROF_GC_OBJ_ARRAY_DUMP record for each object array
DumperSupport::dump_object_array(writer(), objArrayOop(o));
} else if (o->is_typeArray()) {
// create a HPROF_GC_PRIM_ARRAY_DUMP record for each type array
DumperSupport::dump_prim_array(writer(), typeArrayOop(o));
}
}
// The dumper controller for parallel heap dump
class DumperController : public CHeapObj<mtInternal> {
private:
Monitor* _lock;
Mutex* _global_writer_lock;
const uint _dumper_number;
uint _complete_number;
bool _started; // VM dumper started and acquired global writer lock
public:
DumperController(uint number) :
// _lock and _global_writer_lock are used for synchronization between GC worker threads inside safepoint,
// so we lock with _no_safepoint_check_flag.
// signal_start() acquires _lock when global writer is locked,
// its rank must be less than _global_writer_lock rank.
_lock(new (std::nothrow) PaddedMonitor(Mutex::nosafepoint - 1, "DumperController_lock")),
_global_writer_lock(new (std::nothrow) Mutex(Mutex::nosafepoint, "DumpWriter_lock")),
_dumper_number(number),
_complete_number(0),
_started(false)
{}
~DumperController() {
delete _lock;
delete _global_writer_lock;
}
// parallel (non VM) dumpers must wait until VM dumper acquires global writer lock
void wait_for_start_signal() {
MonitorLocker ml(_lock, Mutex::_no_safepoint_check_flag);
while (_started == false) {
ml.wait();
}
}
void signal_start() {
MonitorLocker ml(_lock, Mutex::_no_safepoint_check_flag);
_started = true;
ml.notify_all();
}
void lock_global_writer() {
_global_writer_lock->lock_without_safepoint_check();
}
void unlock_global_writer() {
_global_writer_lock->unlock();
}
void dumper_complete(DumpWriter* local_writer, DumpWriter* global_writer) {
MonitorLocker ml(_lock, Mutex::_no_safepoint_check_flag);
_complete_number++;
// propagate local error to global if any
if (local_writer->has_error()) {
global_writer->set_error(local_writer->error());
}
ml.notify();
}
void wait_all_dumpers_complete() {
MonitorLocker ml(_lock, Mutex::_no_safepoint_check_flag);
while (_complete_number != _dumper_number) {
ml.wait();
}
}
};
// DumpMerger merges separate dump files into a complete one
class DumpMerger : public StackObj {
private:
DumpWriter* _writer;
const char* _path;
bool _has_error;
int _dump_seq;
private:
void merge_file(const char* path);
void merge_done();
void set_error(const char* msg);
public:
DumpMerger(const char* path, DumpWriter* writer, int dump_seq) :
_writer(writer),
_path(path),
_has_error(_writer->has_error()),
_dump_seq(dump_seq) {}
void do_merge();
// returns path for the parallel DumpWriter (resource allocated)
static char* get_writer_path(const char* base_path, int seq);
};
char* DumpMerger::get_writer_path(const char* base_path, int seq) {
// approximate required buffer size
size_t buf_size = strlen(base_path)
+ 2 // ".p"
+ 10 // number (that's enough for 2^32 parallel dumpers)
+ 1; // '\0'
char* path = NEW_RESOURCE_ARRAY(char, buf_size);
memset(path, 0, buf_size);
os::snprintf(path, buf_size, "%s.p%d", base_path, seq);
return path;
}
void DumpMerger::merge_done() {
// Writes the HPROF_HEAP_DUMP_END record.
if (!_has_error) {
DumperSupport::end_of_dump(_writer);
_writer->flush();
}
_dump_seq = 0; //reset
}
void DumpMerger::set_error(const char* msg) {
assert(msg != nullptr, "sanity check");
log_error(heapdump)("%s (file: %s)", msg, _path);
_writer->set_error(msg);
_has_error = true;
}
#ifdef LINUX
// Merge segmented heap files via sendfile, it's more efficient than the
// read+write combination, which would require transferring data to and from
// user space.
void DumpMerger::merge_file(const char* path) {
TraceTime timer("Merge segmented heap file directly", TRACETIME_LOG(Info, heapdump));
int segment_fd = os::open(path, O_RDONLY, 0);
if (segment_fd == -1) {
set_error("Can not open segmented heap file during merging");
return;
}
struct stat st;
if (os::stat(path, &st) != 0) {
::close(segment_fd);
set_error("Can not get segmented heap file size during merging");
return;
}
// A successful call to sendfile may write fewer bytes than requested; the
// caller should be prepared to retry the call if there were unsent bytes.
jlong offset = 0;
while (offset < st.st_size) {
int ret = os::Linux::sendfile(_writer->get_fd(), segment_fd, &offset, st.st_size);
if (ret == -1) {
::close(segment_fd);
set_error("Failed to merge segmented heap file");
return;
}
}
// As sendfile variant does not call the write method of the global writer,
// bytes_written is also incorrect for this variant, we need to explicitly
// accumulate bytes_written for the global writer in this case
julong accum = _writer->bytes_written() + st.st_size;
_writer->set_bytes_written(accum);
::close(segment_fd);
}
#else
// Generic implementation using read+write
void DumpMerger::merge_file(const char* path) {
TraceTime timer("Merge segmented heap file", TRACETIME_LOG(Info, heapdump));
fileStream segment_fs(path, "rb");
if (!segment_fs.is_open()) {
set_error("Can not open segmented heap file during merging");
return;
}
jlong total = 0;
size_t cnt = 0;
// Use _writer buffer for reading.
while ((cnt = segment_fs.read(_writer->buffer(), 1, _writer->buffer_size())) != 0) {
_writer->set_position(cnt);
_writer->flush();
total += cnt;
}
if (segment_fs.fileSize() != total) {
set_error("Merged heap dump is incomplete");
}
}
#endif
void DumpMerger::do_merge() {
TraceTime timer("Merge heap files complete", TRACETIME_LOG(Info, heapdump));
// Since contents in segmented heap file were already zipped, we don't need to zip
// them again during merging.
AbstractCompressor* saved_compressor = _writer->compressor();
_writer->set_compressor(nullptr);
// Merge the content of the remaining files into base file. Regardless of whether
// the merge process is successful or not, these segmented files will be deleted.
for (int i = 0; i < _dump_seq; i++) {
ResourceMark rm;
const char* path = get_writer_path(_path, i);
if (!_has_error) {
merge_file(path);
}
// Delete selected segmented heap file nevertheless
if (remove(path) != 0) {
log_info(heapdump)("Removal of segment file (%d) failed (%d)", i, errno);
}
}
// restore compressor for further use
_writer->set_compressor(saved_compressor);
merge_done();
}
// The VM operation that performs the heap dump
class VM_HeapDumper : public VM_GC_Operation, public WorkerTask, public UnmountedVThreadDumper {
private:
DumpWriter* _writer;
JavaThread* _oome_thread;
Method* _oome_constructor;
bool _gc_before_heap_dump;
GrowableArray<Klass*>* _klass_map;
ThreadDumper** _thread_dumpers; // platform, carrier and mounted virtual threads
int _thread_dumpers_count;
volatile int _thread_serial_num;
volatile int _frame_serial_num;
volatile int _dump_seq;
// parallel heap dump support
uint _num_dumper_threads;
DumperController* _dumper_controller;
ParallelObjectIterator* _poi;
// Dumper id of VMDumper thread.
static const int VMDumperId = 0;
// VM dumper dumps both heap and non-heap data, other dumpers dump heap-only data.
static bool is_vm_dumper(int dumper_id) { return dumper_id == VMDumperId; }
// the 1st dumper calling get_next_dumper_id becomes VM dumper
int get_next_dumper_id() {
return Atomic::fetch_then_add(&_dump_seq, 1);
}
DumpWriter* writer() const { return _writer; }
bool skip_operation() const;
// HPROF_GC_ROOT_THREAD_OBJ records for platform and mounted virtual threads
void dump_threads(AbstractDumpWriter* writer);
bool is_oom_thread(JavaThread* thread) const {
return thread == _oome_thread && _oome_constructor != nullptr;
}
// HPROF_TRACE and HPROF_FRAME records for platform and mounted virtual threads
void dump_stack_traces(AbstractDumpWriter* writer);
public:
VM_HeapDumper(DumpWriter* writer, bool gc_before_heap_dump, bool oome, uint num_dump_threads) :
VM_GC_Operation(0 /* total collections, dummy, ignored */,
GCCause::_heap_dump /* GC Cause */,
0 /* total full collections, dummy, ignored */,
gc_before_heap_dump),
WorkerTask("dump heap") {
_writer = writer;
_gc_before_heap_dump = gc_before_heap_dump;
_klass_map = new (mtServiceability) GrowableArray<Klass*>(INITIAL_CLASS_COUNT, mtServiceability);
_thread_dumpers = nullptr;
_thread_dumpers_count = 0;
_thread_serial_num = 1;
_frame_serial_num = 1;
_dump_seq = VMDumperId;
_num_dumper_threads = num_dump_threads;
_dumper_controller = nullptr;
_poi = nullptr;
if (oome) {
assert(!Thread::current()->is_VM_thread(), "Dump from OutOfMemoryError cannot be called by the VMThread");
// get OutOfMemoryError zero-parameter constructor
InstanceKlass* oome_ik = vmClasses::OutOfMemoryError_klass();
_oome_constructor = oome_ik->find_method(vmSymbols::object_initializer_name(),
vmSymbols::void_method_signature());
// get thread throwing OOME when generating the heap dump at OOME
_oome_thread = JavaThread::current();
} else {
_oome_thread = nullptr;
_oome_constructor = nullptr;
}
}
~VM_HeapDumper() {
if (_thread_dumpers != nullptr) {
for (int i = 0; i < _thread_dumpers_count; i++) {
delete _thread_dumpers[i];
}
FREE_C_HEAP_ARRAY(ThreadDumper*, _thread_dumpers);
}
if (_dumper_controller != nullptr) {
delete _dumper_controller;
_dumper_controller = nullptr;
}
delete _klass_map;
}
int dump_seq() { return _dump_seq; }
bool is_parallel_dump() { return _num_dumper_threads > 1; }
void prepare_parallel_dump(WorkerThreads* workers);
VMOp_Type type() const { return VMOp_HeapDumper; }
virtual bool doit_prologue();
void doit();
void work(uint worker_id);
// UnmountedVThreadDumper implementation
void dump_vthread(oop vt, AbstractDumpWriter* segment_writer);
};
bool VM_HeapDumper::skip_operation() const {
return false;
}
// fixes up the current dump record and writes HPROF_HEAP_DUMP_END record
void DumperSupport::end_of_dump(AbstractDumpWriter* writer) {
writer->finish_dump_segment();
writer->write_u1(HPROF_HEAP_DUMP_END);
writer->write_u4(0);
writer->write_u4(0);
}
// Write a HPROF_GC_ROOT_THREAD_OBJ record for platform/carrier and mounted virtual threads.
// Then walk the stack so that locals and JNI locals are dumped.
void VM_HeapDumper::dump_threads(AbstractDumpWriter* writer) {
for (int i = 0; i < _thread_dumpers_count; i++) {
_thread_dumpers[i]->dump_thread_obj(writer);
_thread_dumpers[i]->dump_stack_refs(writer);
}
}
bool VM_HeapDumper::doit_prologue() {
if (_gc_before_heap_dump && (UseZGC || UseShenandoahGC)) {
// ZGC and Shenandoah cannot perform a synchronous GC cycle from within the VM thread.
// So collect_as_vm_thread() is a noop. To respect the _gc_before_heap_dump flag a
// synchronous GC cycle is performed from the caller thread in the prologue.
Universe::heap()->collect(GCCause::_heap_dump);
}
return VM_GC_Operation::doit_prologue();
}
void VM_HeapDumper::prepare_parallel_dump(WorkerThreads* workers) {
uint num_active_workers = workers != nullptr ? workers->active_workers() : 0;
uint num_requested_dump_threads = _num_dumper_threads;
// check if we can dump in parallel based on requested and active threads
if (num_active_workers <= 1 || num_requested_dump_threads <= 1) {
_num_dumper_threads = 1;
} else {
_num_dumper_threads = clamp(num_requested_dump_threads, 2U, num_active_workers);
}
_dumper_controller = new (std::nothrow) DumperController(_num_dumper_threads);
bool can_parallel = _num_dumper_threads > 1;
log_info(heapdump)("Requested dump threads %u, active dump threads %u, "
"actual dump threads %u, parallelism %s",
num_requested_dump_threads, num_active_workers,
_num_dumper_threads, can_parallel ? "true" : "false");
}
// The VM operation that dumps the heap. The dump consists of the following
// records:
//
// HPROF_HEADER
// [HPROF_UTF8]*
// [HPROF_LOAD_CLASS]*
// [[HPROF_FRAME]*|HPROF_TRACE]*
// [HPROF_GC_CLASS_DUMP]*
// [HPROF_HEAP_DUMP_SEGMENT]*
// HPROF_HEAP_DUMP_END
//
// The HPROF_TRACE records represent the stack traces where the heap dump
// is generated and a "dummy trace" record which does not include
// any frames. The dummy trace record is used to be referenced as the
// unknown object alloc site.
//
// Each HPROF_HEAP_DUMP_SEGMENT record has a length followed by sub-records.
// To allow the heap dump be generated in a single pass we remember the position
// of the dump length and fix it up after all sub-records have been written.
// To generate the sub-records we iterate over the heap, writing
// HPROF_GC_INSTANCE_DUMP, HPROF_GC_OBJ_ARRAY_DUMP, and HPROF_GC_PRIM_ARRAY_DUMP
// records as we go. Once that is done we write records for some of the GC
// roots.
void VM_HeapDumper::doit() {
CollectedHeap* ch = Universe::heap();
ch->ensure_parsability(false); // must happen, even if collection does
// not happen (e.g. due to GCLocker)
if (_gc_before_heap_dump) {
if (GCLocker::is_active()) {
warning("GC locker is held; pre-heapdump GC was skipped");
} else {
ch->collect_as_vm_thread(GCCause::_heap_dump);
}
}
WorkerThreads* workers = ch->safepoint_workers();
prepare_parallel_dump(workers);
if (!is_parallel_dump()) {
work(VMDumperId);
} else {
ParallelObjectIterator poi(_num_dumper_threads);
_poi = &poi;
workers->run_task(this, _num_dumper_threads);
_poi = nullptr;
}
}
void VM_HeapDumper::work(uint worker_id) {
// VM Dumper works on all non-heap data dumping and part of heap iteration.
int dumper_id = get_next_dumper_id();
if (is_vm_dumper(dumper_id)) {
// lock global writer, it will be unlocked after VM Dumper finishes with non-heap data
_dumper_controller->lock_global_writer();
_dumper_controller->signal_start();
} else {
_dumper_controller->wait_for_start_signal();
}
if (is_vm_dumper(dumper_id)) {
TraceTime timer("Dump non-objects", TRACETIME_LOG(Info, heapdump));
// Write the file header - we always use 1.0.2
const char* header = "JAVA PROFILE 1.0.2";
// header is few bytes long - no chance to overflow int
writer()->write_raw(header, strlen(header) + 1); // NUL terminated
writer()->write_u4(oopSize);
// timestamp is current time in ms
writer()->write_u8(os::javaTimeMillis());
// HPROF_UTF8 records
SymbolTableDumper sym_dumper(writer());
SymbolTable::symbols_do(&sym_dumper);
// write HPROF_LOAD_CLASS records
{
LoadedClassDumper loaded_class_dumper(writer(), _klass_map);
ClassLoaderDataGraph::classes_do(&loaded_class_dumper);
}
// write HPROF_FRAME and HPROF_TRACE records
// this must be called after _klass_map is built when iterating the classes above.
dump_stack_traces(writer());
// unlock global writer, so parallel dumpers can dump stack traces of unmounted virtual threads
_dumper_controller->unlock_global_writer();
}
// HPROF_HEAP_DUMP/HPROF_HEAP_DUMP_SEGMENT starts here
ResourceMark rm;
// share global compressor, local DumpWriter is not responsible for its life cycle
DumpWriter segment_writer(DumpMerger::get_writer_path(writer()->get_file_path(), dumper_id),
writer()->is_overwrite(), writer()->compressor());
if (!segment_writer.has_error()) {
if (is_vm_dumper(dumper_id)) {
// dump some non-heap subrecords to heap dump segment
TraceTime timer("Dump non-objects (part 2)", TRACETIME_LOG(Info, heapdump));
// Writes HPROF_GC_CLASS_DUMP records
ClassDumper class_dumper(&segment_writer);
ClassLoaderDataGraph::classes_do(&class_dumper);
// HPROF_GC_ROOT_THREAD_OBJ + frames + jni locals
dump_threads(&segment_writer);
// HPROF_GC_ROOT_JNI_GLOBAL
JNIGlobalsDumper jni_dumper(&segment_writer);
JNIHandles::oops_do(&jni_dumper);
// technically not jni roots, but global roots
// for things like preallocated throwable backtraces
Universe::vm_global()->oops_do(&jni_dumper);
// HPROF_GC_ROOT_STICKY_CLASS
// These should be classes in the null class loader data, and not all classes
// if !ClassUnloading
StickyClassDumper stiky_class_dumper(&segment_writer);
ClassLoaderData::the_null_class_loader_data()->classes_do(&stiky_class_dumper);
}
// Heap iteration.
// writes HPROF_GC_INSTANCE_DUMP records.
// After each sub-record is written check_segment_length will be invoked
// to check if the current segment exceeds a threshold. If so, a new
// segment is started.
// The HPROF_GC_CLASS_DUMP and HPROF_GC_INSTANCE_DUMP are the vast bulk
// of the heap dump.
TraceTime timer(is_parallel_dump() ? "Dump heap objects in parallel" : "Dump heap objects", TRACETIME_LOG(Info, heapdump));
HeapObjectDumper obj_dumper(&segment_writer, this);
if (!is_parallel_dump()) {
Universe::heap()->object_iterate(&obj_dumper);
} else {
// == Parallel dump
_poi->object_iterate(&obj_dumper, worker_id);
}
segment_writer.finish_dump_segment();
segment_writer.flush();
}
_dumper_controller->dumper_complete(&segment_writer, writer());
if (is_vm_dumper(dumper_id)) {
_dumper_controller->wait_all_dumpers_complete();
// flush global writer
writer()->flush();
// At this point, all fragments of the heapdump have been written to separate files.
// We need to merge them into a complete heapdump and write HPROF_HEAP_DUMP_END at that time.
}
}
void VM_HeapDumper::dump_stack_traces(AbstractDumpWriter* writer) {
// write a HPROF_TRACE record without any frames to be referenced as object alloc sites
DumperSupport::write_header(writer, HPROF_TRACE, 3 * sizeof(u4));
writer->write_u4((u4)STACK_TRACE_ID);
writer->write_u4(0); // thread number
writer->write_u4(0); // frame count
// max number if every platform thread is carrier with mounted virtual thread
_thread_dumpers = NEW_C_HEAP_ARRAY(ThreadDumper*, Threads::number_of_threads() * 2, mtInternal);
for (JavaThreadIteratorWithHandle jtiwh; JavaThread * thread = jtiwh.next(); ) {
if (ThreadDumper::should_dump_pthread(thread)) {
bool add_oom_frame = is_oom_thread(thread);
oop mounted_vt = thread->is_vthread_mounted() ? thread->vthread() : nullptr;
if (mounted_vt != nullptr && !ThreadDumper::should_dump_vthread(mounted_vt)) {
mounted_vt = nullptr;
}
// mounted vthread (if any)
if (mounted_vt != nullptr) {
ThreadDumper* thread_dumper = new ThreadDumper(ThreadDumper::ThreadType::MountedVirtual, thread, mounted_vt);
_thread_dumpers[_thread_dumpers_count++] = thread_dumper;
if (add_oom_frame) {
thread_dumper->add_oom_frame(_oome_constructor);
// we add oom frame to the VT stack, don't add it to the carrier thread stack
add_oom_frame = false;
}
thread_dumper->init_serial_nums(&_thread_serial_num, &_frame_serial_num);
thread_dumper->dump_stack_traces(writer, _klass_map);
}
// platform or carrier thread
ThreadDumper* thread_dumper = new ThreadDumper(ThreadDumper::ThreadType::Platform, thread, thread->threadObj());
_thread_dumpers[_thread_dumpers_count++] = thread_dumper;
if (add_oom_frame) {
thread_dumper->add_oom_frame(_oome_constructor);
}
thread_dumper->init_serial_nums(&_thread_serial_num, &_frame_serial_num);
thread_dumper->dump_stack_traces(writer, _klass_map);
}
}
}
void VM_HeapDumper::dump_vthread(oop vt, AbstractDumpWriter* segment_writer) {
// unmounted vthread has no JavaThread
ThreadDumper thread_dumper(ThreadDumper::ThreadType::UnmountedVirtual, nullptr, vt);
thread_dumper.init_serial_nums(&_thread_serial_num, &_frame_serial_num);
// write HPROF_TRACE/HPROF_FRAME records to global writer
_dumper_controller->lock_global_writer();
thread_dumper.dump_stack_traces(writer(), _klass_map);
_dumper_controller->unlock_global_writer();
// write HPROF_GC_ROOT_THREAD_OBJ/HPROF_GC_ROOT_JAVA_FRAME/HPROF_GC_ROOT_JNI_LOCAL subrecord
// to segment writer
thread_dumper.dump_thread_obj(segment_writer);
thread_dumper.dump_stack_refs(segment_writer);
}
// dump the heap to given path.
int HeapDumper::dump(const char* path, outputStream* out, int compression, bool overwrite, uint num_dump_threads) {
assert(path != nullptr && strlen(path) > 0, "path missing");
// print message in interactive case
if (out != nullptr) {
out->print_cr("Dumping heap to %s ...", path);
timer()->start();
}
if (_oome && num_dump_threads > 1) {
// Each additional parallel writer requires several MB of internal memory
// (DumpWriter buffer, DumperClassCacheTable, GZipCompressor buffers).
// For the OOM handling we may already be limited in memory.
// Lets ensure we have at least 20MB per thread.
julong max_threads = os::free_memory() / (20 * M);
if (num_dump_threads > max_threads) {
num_dump_threads = MAX2<uint>(1, (uint)max_threads);
}
}
// create JFR event
EventHeapDump event;
AbstractCompressor* compressor = nullptr;
if (compression > 0) {
compressor = new (std::nothrow) GZipCompressor(compression);
if (compressor == nullptr) {
set_error("Could not allocate gzip compressor");
return -1;
}
}
DumpWriter writer(path, overwrite, compressor);
if (writer.error() != nullptr) {
set_error(writer.error());
if (out != nullptr) {
out->print_cr("Unable to create %s: %s", path,
(error() != nullptr) ? error() : "reason unknown");
}
return -1;
}
// generate the segmented heap dump into separate files
VM_HeapDumper dumper(&writer, _gc_before_heap_dump, _oome, num_dump_threads);
VMThread::execute(&dumper);
// record any error that the writer may have encountered
set_error(writer.error());
// Heap dump process is done in two phases
//
// Phase 1: Concurrent threads directly write heap data to multiple heap files.
// This is done by VM_HeapDumper, which is performed within safepoint.
//
// Phase 2: Merge multiple heap files into one complete heap dump file.
// This is done by DumpMerger, which is performed outside safepoint
DumpMerger merger(path, &writer, dumper.dump_seq());
// Perform heapdump file merge operation in the current thread prevents us
// from occupying the VM Thread, which in turn affects the occurrence of
// GC and other VM operations.
merger.do_merge();
if (writer.error() != nullptr) {
set_error(writer.error());
}
// emit JFR event
if (error() == nullptr) {
event.set_destination(path);
event.set_gcBeforeDump(_gc_before_heap_dump);
event.set_size(writer.bytes_written());
event.set_onOutOfMemoryError(_oome);
event.set_overwrite(overwrite);
event.set_compression(compression);
event.commit();
} else {
log_debug(aot, heap)("Error %s while dumping heap", error());
}
// print message in interactive case
if (out != nullptr) {
timer()->stop();
if (error() == nullptr) {
out->print_cr("Heap dump file created [" JULONG_FORMAT " bytes in %3.3f secs]",
writer.bytes_written(), timer()->seconds());
} else {
out->print_cr("Dump file is incomplete: %s", writer.error());
}
}
if (compressor != nullptr) {
delete compressor;
}
return (writer.error() == nullptr) ? 0 : -1;
}
// stop timer (if still active), and free any error string we might be holding
HeapDumper::~HeapDumper() {
if (timer()->is_active()) {
timer()->stop();
}
set_error(nullptr);
}
// returns the error string (resource allocated), or null
char* HeapDumper::error_as_C_string() const {
if (error() != nullptr) {
char* str = ResourceArea::strdup(error());
return str;
} else {
return nullptr;
}
}
// set the error string
void HeapDumper::set_error(char const* error) {
if (_error != nullptr) {
os::free(_error);
}
if (error == nullptr) {
_error = nullptr;
} else {
_error = os::strdup(error);
assert(_error != nullptr, "allocation failure");
}
}
// Called by out-of-memory error reporting by a single Java thread
// outside of a JVM safepoint
void HeapDumper::dump_heap_from_oome() {
HeapDumper::dump_heap(true);
}
// Called by error reporting by a single Java thread outside of a JVM safepoint,
// or by heap dumping by the VM thread during a (GC) safepoint. Thus, these various
// callers are strictly serialized and guaranteed not to interfere below. For more
// general use, however, this method will need modification to prevent
// inteference when updating the static variables base_path and dump_file_seq below.
void HeapDumper::dump_heap() {
HeapDumper::dump_heap(false);
}
void HeapDumper::dump_heap(bool oome) {
static char base_path[JVM_MAXPATHLEN] = {'\0'};
static uint dump_file_seq = 0;
char my_path[JVM_MAXPATHLEN];
const int max_digit_chars = 20;
const char* dump_file_name = HeapDumpGzipLevel > 0 ? "java_pid%p.hprof.gz" : "java_pid%p.hprof";
// The dump file defaults to java_pid<pid>.hprof in the current working
// directory. HeapDumpPath=<file> can be used to specify an alternative
// dump file name or a directory where dump file is created.
if (dump_file_seq == 0) { // first time in, we initialize base_path
// Set base path (name or directory, default or custom, without seq no), doing %p substitution.
const char *path_src = (HeapDumpPath != nullptr && HeapDumpPath[0] != '\0') ? HeapDumpPath : dump_file_name;
if (!Arguments::copy_expand_pid(path_src, strlen(path_src), base_path, JVM_MAXPATHLEN - max_digit_chars)) {
warning("Cannot create heap dump file. HeapDumpPath is too long.");
return;
}
// Check if the path is an existing directory
DIR* dir = os::opendir(base_path);
if (dir != nullptr) {
os::closedir(dir);
// Path is a directory. Append a file separator (if needed).
size_t fs_len = strlen(os::file_separator());
if (strlen(base_path) >= fs_len) {
char* end = base_path;
end += (strlen(base_path) - fs_len);
if (strcmp(end, os::file_separator()) != 0) {
strcat(base_path, os::file_separator());
}
}
// Then add the default name, with %p substitution. Use my_path temporarily.
if (!Arguments::copy_expand_pid(dump_file_name, strlen(dump_file_name), my_path, JVM_MAXPATHLEN - max_digit_chars)) {
warning("Cannot create heap dump file. HeapDumpPath is too long.");
return;
}
const size_t dlen = strlen(base_path);
jio_snprintf(&base_path[dlen], sizeof(base_path) - dlen, "%s", my_path);
}
strncpy(my_path, base_path, JVM_MAXPATHLEN);
} else {
// Append a sequence number id for dumps following the first
const size_t len = strlen(base_path) + max_digit_chars + 2; // for '.' and \0
jio_snprintf(my_path, len, "%s.%d", base_path, dump_file_seq);
}
dump_file_seq++; // increment seq number for next time we dump
HeapDumper dumper(false /* no GC before heap dump */,
oome /* pass along out-of-memory-error flag */);
dumper.dump(my_path, tty, HeapDumpGzipLevel);
}