What is the exact behavior of AsyncContext after it times out? Does it still run and does it return response using getResponse()?

解决方案

Java Servlet 3.0 Maintenance Release on page 34 reads:

A call to this method - ServletRequest.startAsync(ServletRequest req,

ServletResponse res) - ensures that the response isn't committed when

the application exits out of the service method. It is committed when

AsyncContext.complete is called on the returned AsyncContext or the

AsyncContext times out and there are no listeners associated to handle

the time out. The timer for async time outs will not start until the

request and it’s associated response have returned from the container.

The AsyncContext could be used to write to the response from the async

thread. It can also be used to just notify that the response is not

closed and committed.

In the event that an asynchronous operation has timed out, the

container must run through these steps:

Invoke, at their onTimeout method, all AsyncListener instances registered with the ServletRequest on which the asynchronous operation

was initiated.

If none of the listeners called complete() or any of the dispatch() methods, perform an error dispatch with a status code equal

to HttpServletResponse.SC_INTERNAL_SERVER_ERROR.

If no matching error page was found, or the error page did not call complete() or any of the dispatch() methods, call complete()."

The last line above is of most importance - there'll be a call to AsyncContext.complete(). The javadoc says:

Completes the asynchronous operation that was started on the request

that was used to initialze this AsyncContext, closing the response

that was used to initialize this AsyncContext.

With AsyncContext closed, calls to most of its methods will throw IllegalStateException.