RFR: 8297424: java/net/httpclient/AsyncExecutorShutdown.java fails in AssertionError due to misplaced assert [v2]

[Jaikiran Pai]

On Fri, 25 Nov 2022 10:22:10 GMT, Daniel Fuchs <dfuchs at openjdk.org> wrote:

>> The `ResponseSubscribers.HttpResponseInputStream` class has an assert that has been observed firing (rarely) when running the `java/net/httpclient/AsyncExecutorShutdown.java` test.
>> 
>> After a thorough analysis of the code and the log failure I am convinced that the issue is due to a misplaced assert.
>> If cancellation happens asynchronously while the subscriber is being subscribed with the lower layers of the stack, the `HttpResponseInputStream` might get closed and the `LAST_LIST` buffer might be offered after `closed == false` has been observed by the `onSubscribed` method, but before the assertion has been checked. The assertion assumes that the queue must be empty, but it might not if `close` has been called and the `LAST_LIST` buffer has been offered.
>> 
>> Moving the assert from within the synchronized block, to ensure that the observed value of `closed` is consistent with the state of the queue, should fix it. I have tagged the bug as `noreg-hard`, I'm not sure it would be fair to say that `AsyncExecutorShutdown.java` can be used to verify the fix.
>
> Daniel Fuchs has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:
> 
>  - Merge branch 'master' into AsyncExecutorShutdown-8297424
>  - Revert assignement of pendingResponseSubscriber to null to avoid race conditions with ternary operators
>  - 8297424

Thank you Daniel. The latest changes look good to me.

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Marked as reviewed by jpai (Reviewer).

PR: https://git.openjdk.org/jdk/pull/11332