src/hotspot/share/gc/g1/g1MonitoringSupport.cpp - openjdk/jdk25u - Git at Google

 /*
  * Copyright (c) 2011, 2025, Oracle and/or its affiliates. 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 "gc/g1/g1CollectedHeap.inline.hpp"
 #include "gc/g1/g1MemoryPool.hpp"
 #include "gc/g1/g1MonitoringSupport.hpp"
 #include "gc/g1/g1Policy.hpp"
 #include "gc/shared/hSpaceCounters.hpp"
 #include "memory/metaspaceCounters.hpp"
 #include "runtime/mutexLocker.hpp"
 #include "services/memoryPool.hpp"

 class G1GenerationCounters : public GenerationCounters {
 protected:
   G1MonitoringSupport* _monitoring_support;

 public:
   G1GenerationCounters(G1MonitoringSupport* monitoring_support,
                        const char* name, int ordinal, int spaces,
                        size_t min_capacity, size_t max_capacity,
                        size_t curr_capacity) :
     GenerationCounters(name, ordinal, spaces, min_capacity,
                        max_capacity, curr_capacity),
     _monitoring_support(monitoring_support) { }
 };

 class G1YoungGenerationCounters : public G1GenerationCounters {
 public:
   G1YoungGenerationCounters(G1MonitoringSupport* monitoring_support, const char* name, size_t max_size) :
     G1GenerationCounters(monitoring_support,
                          name,
                          0 /* ordinal */,
                          3 /* spaces */,
                          0 /* min_capacity */,
                          max_size,
                          0 /* curr_capacity */) {
     if (UsePerfData) {
       update_all();
     }
   }

   void update_all() {
     size_t committed = _monitoring_support->young_gen_committed();
     GenerationCounters::update_all(committed);
   }
 };

 class G1OldGenerationCounters : public G1GenerationCounters {
 public:
   G1OldGenerationCounters(G1MonitoringSupport* monitoring_support, const char* name, size_t max_size) :
     G1GenerationCounters(monitoring_support,
                          name,
                          1 /* ordinal */,
                          1 /* spaces */,
                          0 /* min_capacity */,
                          max_size,
                          0 /* curr_capacity */) {
     if (UsePerfData) {
       update_all();
     }
   }

   void update_all() {
     size_t committed = _monitoring_support->old_gen_committed();
     GenerationCounters::update_all(committed);
   }
 };

 G1MonitoringSupport::G1MonitoringSupport(G1CollectedHeap* g1h) :
   _g1h(g1h),
   _young_gc_memory_manager("G1 Young Generation"),
   _full_gc_memory_manager("G1 Old Generation"),
   _conc_gc_memory_manager("G1 Concurrent GC"),
   _eden_space_pool(nullptr),
   _survivor_space_pool(nullptr),
   _old_gen_pool(nullptr),
   _young_collection_counters(nullptr),
   _full_collection_counters(nullptr),
   _conc_collection_counters(nullptr),
   _young_gen_counters(nullptr),
   _old_gen_counters(nullptr),
   _old_space_counters(nullptr),
   _eden_space_counters(nullptr),
   _from_space_counters(nullptr),
   _to_space_counters(nullptr),

   _overall_committed(0),
   _overall_used(0),
   _young_gen_committed(0),
   _old_gen_committed(0),

   _eden_space_committed(0),
   _eden_space_used(0),
   _survivor_space_committed(0),
   _survivor_space_used(0),
   _old_gen_used(0) {

   recalculate_sizes();

   // Counters for garbage collections
   //
   //  name "collector.0".  In a generational collector this would be the
   // young generation collection.
   _young_collection_counters =
     new CollectorCounters("G1 young collection pauses", 0);
   //   name "collector.1".  In a generational collector this would be the
   // old generation collection.
   _full_collection_counters =
     new CollectorCounters("G1 full collection pauses", 1);
   //   name "collector.2".  In a generational collector this would be the
   // STW phases in concurrent collection.
   _conc_collection_counters =
     new CollectorCounters("G1 concurrent cycle pauses", 2);

   // "Generation" and "Space" counters.
   //
   //  name "generation.1" This is logically the old generation in
   // generational GC terms.  The "1, 1" parameters are for
   // the n-th generation (=1) with 1 space.
   // Counters are created from minCapacity, maxCapacity, and capacity
   _old_gen_counters = new G1OldGenerationCounters(this, "old", _g1h->max_capacity());

   //  name  "generation.1.space.0"
   // Counters are created from maxCapacity, capacity, initCapacity,
   // and used.
   _old_space_counters = new HSpaceCounters(_old_gen_counters->name_space(),
                                            "space", 0 /* ordinal */,
                                            g1h->max_capacity() /* max_capacity */,
                                            _old_gen_committed /* init_capacity */);

   //   Young collection set
   //  name "generation.0".  This is logically the young generation.
   //  The "0, 3" are parameters for the n-th generation (=0) with 3 spaces.
   // See  _old_collection_counters for additional counters
   _young_gen_counters = new G1YoungGenerationCounters(this, "young", _g1h->max_capacity());

   const char* young_collection_name_space = _young_gen_counters->name_space();

   //  name "generation.0.space.0"
   // See _old_space_counters for additional counters
   _eden_space_counters = new HSpaceCounters(young_collection_name_space,
                                             "eden", 0 /* ordinal */,
                                             g1h->max_capacity() /* max_capacity */,
                                             _eden_space_committed /* init_capacity */);

   //  name "generation.0.space.1"
   // See _old_space_counters for additional counters
   // Set the arguments to indicate that this survivor space is not used.
   _from_space_counters = new HSpaceCounters(young_collection_name_space,
                                             "s0", 1 /* ordinal */,
                                             0 /* max_capacity */,
                                             0 /* init_capacity */);
   // Given that this survivor space is not used, we update it here
   // once to reflect that its used space is 0 so that we don't have to
   // worry about updating it again later.
   if (UsePerfData) {
     _from_space_counters->update_used(0);
   }

   //  name "generation.0.space.2"
   // See _old_space_counters for additional counters
   _to_space_counters = new HSpaceCounters(young_collection_name_space,
                                           "s1", 2 /* ordinal */,
                                           g1h->max_capacity() /* max_capacity */,
                                           _survivor_space_committed /* init_capacity */);
 }

 G1MonitoringSupport::~G1MonitoringSupport() {
   delete _eden_space_pool;
   delete _survivor_space_pool;
   delete _old_gen_pool;
 }

 void G1MonitoringSupport::initialize_serviceability() {
   _eden_space_pool = new G1EdenPool(_g1h, _eden_space_committed);
   _survivor_space_pool = new G1SurvivorPool(_g1h, _survivor_space_committed);
   _old_gen_pool = new G1OldGenPool(_g1h, _old_gen_committed, _g1h->max_capacity());

   _full_gc_memory_manager.add_pool(_eden_space_pool);
   _full_gc_memory_manager.add_pool(_survivor_space_pool);
   _full_gc_memory_manager.add_pool(_old_gen_pool);

   _conc_gc_memory_manager.add_pool(_old_gen_pool);

   _young_gc_memory_manager.add_pool(_eden_space_pool);
   _young_gc_memory_manager.add_pool(_survivor_space_pool);
   _young_gc_memory_manager.add_pool(_old_gen_pool, false /* always_affected_by_gc */);
 }

 MemoryUsage G1MonitoringSupport::memory_usage() {
   MutexLocker x(MonitoringSupport_lock, Mutex::_no_safepoint_check_flag);
   return MemoryUsage(InitialHeapSize, _overall_used, _overall_committed, _g1h->max_capacity());
 }

 GrowableArray<GCMemoryManager*> G1MonitoringSupport::memory_managers() {
   GrowableArray<GCMemoryManager*> memory_managers(3);
   memory_managers.append(&_young_gc_memory_manager);
   memory_managers.append(&_full_gc_memory_manager);
   memory_managers.append(&_conc_gc_memory_manager);
   return memory_managers;
 }

 GrowableArray<MemoryPool*> G1MonitoringSupport::memory_pools() {
   GrowableArray<MemoryPool*> memory_pools(3);
   memory_pools.append(_eden_space_pool);
   memory_pools.append(_survivor_space_pool);
   memory_pools.append(_old_gen_pool);
   return memory_pools;
 }

 void G1MonitoringSupport::recalculate_sizes() {
   assert_heap_locked_or_at_safepoint(true);

   MutexLocker x(MonitoringSupport_lock, Mutex::_no_safepoint_check_flag);
   // Recalculate all the sizes from scratch.

   // This never includes used bytes of current allocating heap region.
   _overall_used = _g1h->used_unlocked();
   _eden_space_used = _g1h->eden_regions_used_bytes();
   _survivor_space_used = _g1h->survivor_regions_used_bytes();

   // _overall_used and _eden_space_used are obtained concurrently so
   // may be inconsistent with each other. To prevent _old_gen_used going negative,
   // use smaller value to subtract.
   _old_gen_used = _overall_used - MIN2(_overall_used, _eden_space_used + _survivor_space_used);

   uint survivor_list_length = _g1h->survivor_regions_count();

   uint young_list_target_length = _g1h->policy()->young_list_target_length();
   assert(young_list_target_length >= survivor_list_length, "invariant");
   uint eden_list_max_length = young_list_target_length - survivor_list_length;

   // First calculate the committed sizes that can be calculated independently.
   _survivor_space_committed = survivor_list_length * G1HeapRegion::GrainBytes;
   _old_gen_committed = G1HeapRegion::align_up_to_region_byte_size(_old_gen_used);

   // Next, start with the overall committed size.
   _overall_committed = _g1h->capacity();
   size_t committed = _overall_committed;

   // Remove the committed size we have calculated so far (for the
   // survivor and old space).
   assert(committed >= (_survivor_space_committed + _old_gen_committed), "sanity");
   committed -= _survivor_space_committed + _old_gen_committed;

   // Next, calculate and remove the committed size for the eden.
   _eden_space_committed = (size_t) eden_list_max_length * G1HeapRegion::GrainBytes;
   // Somewhat defensive: be robust in case there are inaccuracies in
   // the calculations
   _eden_space_committed = MIN2(_eden_space_committed, committed);
   committed -= _eden_space_committed;

   // Finally, give the rest to the old space...
   _old_gen_committed += committed;
   // ..and calculate the young gen committed.
   _young_gen_committed = _eden_space_committed + _survivor_space_committed;

   assert(_overall_committed ==
          (_eden_space_committed + _survivor_space_committed + _old_gen_committed),
          "the committed sizes should add up");
   // Somewhat defensive: cap the eden used size to make sure it
   // never exceeds the committed size.
   _eden_space_used = MIN2(_eden_space_used, _eden_space_committed);
   // _survivor_space_used is calculated during a safepoint and _survivor_space_committed
   // is calculated from survivor region count * heap region size.
   assert(_survivor_space_used <= _survivor_space_committed, "Survivor used bytes(%zu)"
          " should be less than or equal to survivor committed(%zu)",
          _survivor_space_used, _survivor_space_committed);
   // _old_gen_committed is calculated in terms of _old_gen_used value.
   assert(_old_gen_used <= _old_gen_committed, "Old gen used bytes(%zu)"
          " should be less than or equal to old gen committed(%zu)",
          _old_gen_used, _old_gen_committed);
 }

 void G1MonitoringSupport::update_sizes() {
   recalculate_sizes();
   if (UsePerfData) {
     _eden_space_counters->update_capacity(_eden_space_committed);
     _eden_space_counters->update_used(_eden_space_used);
     // only the "to" survivor space is active, so we don't need to
     // update the counters for the "from" survivor space
     _to_space_counters->update_capacity(_survivor_space_committed);
     _to_space_counters->update_used(_survivor_space_used);
     _old_space_counters->update_capacity(_old_gen_committed);
     _old_space_counters->update_used(_old_gen_used);

     _young_gen_counters->update_all();
     _old_gen_counters->update_all();

     MetaspaceCounters::update_performance_counters();
   }
 }

 void G1MonitoringSupport::update_eden_size() {
   // Recalculate everything - this should be fast enough and we are sure that we do not
   // miss anything.
   recalculate_sizes();
   if (UsePerfData) {
     _eden_space_counters->update_used(_eden_space_used);
   }
 }

 MemoryUsage G1MonitoringSupport::eden_space_memory_usage(size_t initial_size, size_t max_size) {
   MutexLocker x(MonitoringSupport_lock, Mutex::_no_safepoint_check_flag);

   return MemoryUsage(initial_size,
                      _eden_space_used,
                      _eden_space_committed,
                      max_size);
 }

 MemoryUsage G1MonitoringSupport::survivor_space_memory_usage(size_t initial_size, size_t max_size) {
   MutexLocker x(MonitoringSupport_lock, Mutex::_no_safepoint_check_flag);

   return MemoryUsage(initial_size,
                      _survivor_space_used,
                      _survivor_space_committed,
                      max_size);
 }

 MemoryUsage G1MonitoringSupport::old_gen_memory_usage(size_t initial_size, size_t max_size) {
   MutexLocker x(MonitoringSupport_lock, Mutex::_no_safepoint_check_flag);

   return MemoryUsage(initial_size,
                      _old_gen_used,
                      _old_gen_committed,
                      max_size);
 }

 G1MonitoringScope::G1MonitoringScope(G1MonitoringSupport* monitoring_support,
                                      CollectorCounters* collection_counters,
                                      GCMemoryManager* gc_memory_manager,
                                      const char* end_message,
                                      bool all_memory_pools_affected) :
   _monitoring_support(monitoring_support),
   _tcs(collection_counters),
   _tms(gc_memory_manager,
        G1CollectedHeap::heap()->gc_cause(),
        end_message,
        all_memory_pools_affected) {
 }

 G1MonitoringScope::~G1MonitoringScope() {
   _monitoring_support->update_sizes();
   // Needs to be called after updating pool sizes.
   MemoryService::track_memory_usage();
 }

 G1YoungGCMonitoringScope::G1YoungGCMonitoringScope(G1MonitoringSupport* monitoring_support,
                                                    bool all_memory_pools_affected) :
   G1MonitoringScope(monitoring_support,
                     monitoring_support->_young_collection_counters,
                     &monitoring_support->_young_gc_memory_manager,
                     "end of minor GC",
                     all_memory_pools_affected) {
 }

 G1FullGCMonitoringScope::G1FullGCMonitoringScope(G1MonitoringSupport* monitoring_support) :
   G1MonitoringScope(monitoring_support,
                     monitoring_support->_full_collection_counters,
                     &monitoring_support->_full_gc_memory_manager,
                     "end of major GC") {
 }

 G1ConcGCMonitoringScope::G1ConcGCMonitoringScope(G1MonitoringSupport* monitoring_support) :
   G1MonitoringScope(monitoring_support,
                     monitoring_support->_conc_collection_counters,
                     &monitoring_support->_conc_gc_memory_manager,
                     "end of concurrent GC pause") {
 }
	/*
	* Copyright (c) 2011, 2025, Oracle and/or its affiliates. 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 "gc/g1/g1CollectedHeap.inline.hpp"
	#include "gc/g1/g1MemoryPool.hpp"
	#include "gc/g1/g1MonitoringSupport.hpp"
	#include "gc/g1/g1Policy.hpp"
	#include "gc/shared/hSpaceCounters.hpp"
	#include "memory/metaspaceCounters.hpp"
	#include "runtime/mutexLocker.hpp"
	#include "services/memoryPool.hpp"

	class G1GenerationCounters : public GenerationCounters {
	protected:
	G1MonitoringSupport* _monitoring_support;

	public:
	G1GenerationCounters(G1MonitoringSupport* monitoring_support,
	const char* name, int ordinal, int spaces,
	size_t min_capacity, size_t max_capacity,
	size_t curr_capacity) :
	GenerationCounters(name, ordinal, spaces, min_capacity,
	max_capacity, curr_capacity),
	_monitoring_support(monitoring_support) { }
	};

	class G1YoungGenerationCounters : public G1GenerationCounters {
	public:
	G1YoungGenerationCounters(G1MonitoringSupport* monitoring_support, const char* name, size_t max_size) :
	G1GenerationCounters(monitoring_support,
	name,
	0 /* ordinal */,
	3 /* spaces */,
	0 /* min_capacity */,
	max_size,
	0 /* curr_capacity */) {
	if (UsePerfData) {
	update_all();
	}
	}

	void update_all() {
	size_t committed = _monitoring_support->young_gen_committed();
	GenerationCounters::update_all(committed);
	}
	};

	class G1OldGenerationCounters : public G1GenerationCounters {
	public:
	G1OldGenerationCounters(G1MonitoringSupport* monitoring_support, const char* name, size_t max_size) :
	G1GenerationCounters(monitoring_support,
	name,
	1 /* ordinal */,
	1 /* spaces */,
	0 /* min_capacity */,
	max_size,
	0 /* curr_capacity */) {
	if (UsePerfData) {
	update_all();
	}
	}

	void update_all() {
	size_t committed = _monitoring_support->old_gen_committed();
	GenerationCounters::update_all(committed);
	}
	};

	G1MonitoringSupport::G1MonitoringSupport(G1CollectedHeap* g1h) :
	_g1h(g1h),
	_young_gc_memory_manager("G1 Young Generation"),
	_full_gc_memory_manager("G1 Old Generation"),
	_conc_gc_memory_manager("G1 Concurrent GC"),
	_eden_space_pool(nullptr),
	_survivor_space_pool(nullptr),
	_old_gen_pool(nullptr),
	_young_collection_counters(nullptr),
	_full_collection_counters(nullptr),
	_conc_collection_counters(nullptr),
	_young_gen_counters(nullptr),
	_old_gen_counters(nullptr),
	_old_space_counters(nullptr),
	_eden_space_counters(nullptr),
	_from_space_counters(nullptr),
	_to_space_counters(nullptr),

	_overall_committed(0),
	_overall_used(0),
	_young_gen_committed(0),
	_old_gen_committed(0),

	_eden_space_committed(0),
	_eden_space_used(0),
	_survivor_space_committed(0),
	_survivor_space_used(0),
	_old_gen_used(0) {

	recalculate_sizes();

	// Counters for garbage collections
	//
	// name "collector.0". In a generational collector this would be the
	// young generation collection.
	_young_collection_counters =
	new CollectorCounters("G1 young collection pauses", 0);
	// name "collector.1". In a generational collector this would be the
	// old generation collection.
	_full_collection_counters =
	new CollectorCounters("G1 full collection pauses", 1);
	// name "collector.2". In a generational collector this would be the
	// STW phases in concurrent collection.
	_conc_collection_counters =
	new CollectorCounters("G1 concurrent cycle pauses", 2);

	// "Generation" and "Space" counters.
	//
	// name "generation.1" This is logically the old generation in
	// generational GC terms. The "1, 1" parameters are for
	// the n-th generation (=1) with 1 space.
	// Counters are created from minCapacity, maxCapacity, and capacity
	_old_gen_counters = new G1OldGenerationCounters(this, "old", _g1h->max_capacity());

	// name "generation.1.space.0"
	// Counters are created from maxCapacity, capacity, initCapacity,
	// and used.
	_old_space_counters = new HSpaceCounters(_old_gen_counters->name_space(),
	"space", 0 /* ordinal */,
	g1h->max_capacity() /* max_capacity */,
	_old_gen_committed /* init_capacity */);

	// Young collection set
	// name "generation.0". This is logically the young generation.
	// The "0, 3" are parameters for the n-th generation (=0) with 3 spaces.
	// See _old_collection_counters for additional counters
	_young_gen_counters = new G1YoungGenerationCounters(this, "young", _g1h->max_capacity());

	const char* young_collection_name_space = _young_gen_counters->name_space();

	// name "generation.0.space.0"
	// See _old_space_counters for additional counters
	_eden_space_counters = new HSpaceCounters(young_collection_name_space,
	"eden", 0 /* ordinal */,
	g1h->max_capacity() /* max_capacity */,
	_eden_space_committed /* init_capacity */);

	// name "generation.0.space.1"
	// See _old_space_counters for additional counters
	// Set the arguments to indicate that this survivor space is not used.
	_from_space_counters = new HSpaceCounters(young_collection_name_space,
	"s0", 1 /* ordinal */,
	0 /* max_capacity */,
	0 /* init_capacity */);
	// Given that this survivor space is not used, we update it here
	// once to reflect that its used space is 0 so that we don't have to
	// worry about updating it again later.
	if (UsePerfData) {
	_from_space_counters->update_used(0);
	}

	// name "generation.0.space.2"
	// See _old_space_counters for additional counters
	_to_space_counters = new HSpaceCounters(young_collection_name_space,
	"s1", 2 /* ordinal */,
	g1h->max_capacity() /* max_capacity */,
	_survivor_space_committed /* init_capacity */);
	}

	G1MonitoringSupport::~G1MonitoringSupport() {
	delete _eden_space_pool;
	delete _survivor_space_pool;
	delete _old_gen_pool;
	}

	void G1MonitoringSupport::initialize_serviceability() {
	_eden_space_pool = new G1EdenPool(_g1h, _eden_space_committed);
	_survivor_space_pool = new G1SurvivorPool(_g1h, _survivor_space_committed);
	_old_gen_pool = new G1OldGenPool(_g1h, _old_gen_committed, _g1h->max_capacity());

	_full_gc_memory_manager.add_pool(_eden_space_pool);
	_full_gc_memory_manager.add_pool(_survivor_space_pool);
	_full_gc_memory_manager.add_pool(_old_gen_pool);

	_conc_gc_memory_manager.add_pool(_old_gen_pool);

	_young_gc_memory_manager.add_pool(_eden_space_pool);
	_young_gc_memory_manager.add_pool(_survivor_space_pool);
	_young_gc_memory_manager.add_pool(_old_gen_pool, false /* always_affected_by_gc */);
	}

	MemoryUsage G1MonitoringSupport::memory_usage() {
	MutexLocker x(MonitoringSupport_lock, Mutex::_no_safepoint_check_flag);
	return MemoryUsage(InitialHeapSize, _overall_used, _overall_committed, _g1h->max_capacity());
	}

	GrowableArray<GCMemoryManager*> G1MonitoringSupport::memory_managers() {
	GrowableArray<GCMemoryManager*> memory_managers(3);
	memory_managers.append(&_young_gc_memory_manager);
	memory_managers.append(&_full_gc_memory_manager);
	memory_managers.append(&_conc_gc_memory_manager);
	return memory_managers;
	}

	GrowableArray<MemoryPool*> G1MonitoringSupport::memory_pools() {
	GrowableArray<MemoryPool*> memory_pools(3);
	memory_pools.append(_eden_space_pool);
	memory_pools.append(_survivor_space_pool);
	memory_pools.append(_old_gen_pool);
	return memory_pools;
	}

	void G1MonitoringSupport::recalculate_sizes() {
	assert_heap_locked_or_at_safepoint(true);

	MutexLocker x(MonitoringSupport_lock, Mutex::_no_safepoint_check_flag);
	// Recalculate all the sizes from scratch.

	// This never includes used bytes of current allocating heap region.
	_overall_used = _g1h->used_unlocked();
	_eden_space_used = _g1h->eden_regions_used_bytes();
	_survivor_space_used = _g1h->survivor_regions_used_bytes();

	// _overall_used and _eden_space_used are obtained concurrently so
	// may be inconsistent with each other. To prevent _old_gen_used going negative,
	// use smaller value to subtract.
	_old_gen_used = _overall_used - MIN2(_overall_used, _eden_space_used + _survivor_space_used);

	uint survivor_list_length = _g1h->survivor_regions_count();

	uint young_list_target_length = _g1h->policy()->young_list_target_length();
	assert(young_list_target_length >= survivor_list_length, "invariant");
	uint eden_list_max_length = young_list_target_length - survivor_list_length;

	// First calculate the committed sizes that can be calculated independently.
	_survivor_space_committed = survivor_list_length * G1HeapRegion::GrainBytes;
	_old_gen_committed = G1HeapRegion::align_up_to_region_byte_size(_old_gen_used);

	// Next, start with the overall committed size.
	_overall_committed = _g1h->capacity();
	size_t committed = _overall_committed;

	// Remove the committed size we have calculated so far (for the
	// survivor and old space).
	assert(committed >= (_survivor_space_committed + _old_gen_committed), "sanity");
	committed -= _survivor_space_committed + _old_gen_committed;

	// Next, calculate and remove the committed size for the eden.
	_eden_space_committed = (size_t) eden_list_max_length * G1HeapRegion::GrainBytes;
	// Somewhat defensive: be robust in case there are inaccuracies in
	// the calculations
	_eden_space_committed = MIN2(_eden_space_committed, committed);
	committed -= _eden_space_committed;

	// Finally, give the rest to the old space...
	_old_gen_committed += committed;
	// ..and calculate the young gen committed.
	_young_gen_committed = _eden_space_committed + _survivor_space_committed;

	assert(_overall_committed ==
	(_eden_space_committed + _survivor_space_committed + _old_gen_committed),
	"the committed sizes should add up");
	// Somewhat defensive: cap the eden used size to make sure it
	// never exceeds the committed size.
	_eden_space_used = MIN2(_eden_space_used, _eden_space_committed);
	// _survivor_space_used is calculated during a safepoint and _survivor_space_committed
	// is calculated from survivor region count * heap region size.
	assert(_survivor_space_used <= _survivor_space_committed, "Survivor used bytes(%zu)"
	" should be less than or equal to survivor committed(%zu)",
	_survivor_space_used, _survivor_space_committed);
	// _old_gen_committed is calculated in terms of _old_gen_used value.
	assert(_old_gen_used <= _old_gen_committed, "Old gen used bytes(%zu)"
	" should be less than or equal to old gen committed(%zu)",
	_old_gen_used, _old_gen_committed);
	}

	void G1MonitoringSupport::update_sizes() {
	recalculate_sizes();
	if (UsePerfData) {
	_eden_space_counters->update_capacity(_eden_space_committed);
	_eden_space_counters->update_used(_eden_space_used);
	// only the "to" survivor space is active, so we don't need to
	// update the counters for the "from" survivor space
	_to_space_counters->update_capacity(_survivor_space_committed);
	_to_space_counters->update_used(_survivor_space_used);
	_old_space_counters->update_capacity(_old_gen_committed);
	_old_space_counters->update_used(_old_gen_used);

	_young_gen_counters->update_all();
	_old_gen_counters->update_all();

	MetaspaceCounters::update_performance_counters();
	}
	}

	void G1MonitoringSupport::update_eden_size() {
	// Recalculate everything - this should be fast enough and we are sure that we do not
	// miss anything.
	recalculate_sizes();
	if (UsePerfData) {
	_eden_space_counters->update_used(_eden_space_used);
	}
	}

	MemoryUsage G1MonitoringSupport::eden_space_memory_usage(size_t initial_size, size_t max_size) {
	MutexLocker x(MonitoringSupport_lock, Mutex::_no_safepoint_check_flag);

	return MemoryUsage(initial_size,
	_eden_space_used,
	_eden_space_committed,
	max_size);
	}

	MemoryUsage G1MonitoringSupport::survivor_space_memory_usage(size_t initial_size, size_t max_size) {
	MutexLocker x(MonitoringSupport_lock, Mutex::_no_safepoint_check_flag);

	return MemoryUsage(initial_size,
	_survivor_space_used,
	_survivor_space_committed,
	max_size);
	}

	MemoryUsage G1MonitoringSupport::old_gen_memory_usage(size_t initial_size, size_t max_size) {
	MutexLocker x(MonitoringSupport_lock, Mutex::_no_safepoint_check_flag);

	return MemoryUsage(initial_size,
	_old_gen_used,
	_old_gen_committed,
	max_size);
	}

	G1MonitoringScope::G1MonitoringScope(G1MonitoringSupport* monitoring_support,
	CollectorCounters* collection_counters,
	GCMemoryManager* gc_memory_manager,
	const char* end_message,
	bool all_memory_pools_affected) :
	_monitoring_support(monitoring_support),
	_tcs(collection_counters),
	_tms(gc_memory_manager,
	G1CollectedHeap::heap()->gc_cause(),
	end_message,
	all_memory_pools_affected) {
	}

	G1MonitoringScope::~G1MonitoringScope() {
	_monitoring_support->update_sizes();
	// Needs to be called after updating pool sizes.
	MemoryService::track_memory_usage();
	}

	G1YoungGCMonitoringScope::G1YoungGCMonitoringScope(G1MonitoringSupport* monitoring_support,
	bool all_memory_pools_affected) :
	G1MonitoringScope(monitoring_support,
	monitoring_support->_young_collection_counters,
	&monitoring_support->_young_gc_memory_manager,
	"end of minor GC",
	all_memory_pools_affected) {
	}

	G1FullGCMonitoringScope::G1FullGCMonitoringScope(G1MonitoringSupport* monitoring_support) :
	G1MonitoringScope(monitoring_support,
	monitoring_support->_full_collection_counters,
	&monitoring_support->_full_gc_memory_manager,
	"end of major GC") {
	}

	G1ConcGCMonitoringScope::G1ConcGCMonitoringScope(G1MonitoringSupport* monitoring_support) :
	G1MonitoringScope(monitoring_support,
	monitoring_support->_conc_collection_counters,
	&monitoring_support->_conc_gc_memory_manager,
	"end of concurrent GC pause") {
	}