Server Asynchronous Managed Example

This example demonstrates JAX-RS 2.0 server-side non-blocking API using ManagedAsync annotation.

The full description how to create an asynchronous resource can be found in Jersey User Guide, chapter Asynchronous Services and Clients.

Indicates that the resource method to which the annotation has been applied

• should be executed on a separate thread managed by an internal Jersey

The goal of the sample is to demonstrate that with limited I/O processing threads on the server the synchronous execution of a long-running task may lead to resource starvation caused by I/O processing threads being blocked by the long-running operation, unable to serve new incoming requests.

OTOH, when the same long-running operation is executed asynchronously, the I/O threads do not need to block while waiting for the long-running operation to finish and the overall throughput of the system is greatly increased.

• Look at the another example how to create a non-blocking API without ManagedAsync annotation https://github.com/jersey/jersey/tree/master/examples/server-async which also shown the way how to provide an immediate response for a client

Contents

The mapping of the URI path space is presented in the following table:

Sample Response

This section shortly describes what really happens during the calls in this chat example.

We can start with POST request:

curl -v -X POST http://localhost:8080/base/chat -H "Content-Type: application/json" -d '{
    "author": "Anonymous Author",
    "message": "Secret Message"
}'

We can notice that we haven‘t got any response yet. The called method is annotated @ManagedAsync which means that the I/O thread delegates a method processing to another Thread-Pool and is ready to accept another incoming request. But the processing is still stop. Why? AsyncResponse was added to the blocking queue and now it’s waiting for GET call which will take the response and will finish the processing of the preceding call.

curl -v -X GET http://localhost:8080/base/chat

Running the Example

Run the example as follows:

mvn clean compile exec:java

This deploys the example using Grizzly container.