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

[Jaikiran Pai]

On Wed, 23 Nov 2022 19:38:50 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.

Hello Daniel, the change where we move the assert into the synchronized block looks fine to me. Looking at the code I think the check to see that the `buffers` can accomodate at least 2 elements (when `onSubscribe` is called) looks correct to me because the `buffers` will be initialized in the constructor of `HttpResponseInputStream` with a capacity of at least 2. So the assert itself looks correct.

This PR also has changes in the `Stream` class. Some of those changes are typo related fixes, so that's fine. However, it also has other functional changes. Is that intentional and related?

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