RFR: 8317808: HTTP/2 stream cancelImpl may leave subscriber registered [v2]

[Michael McMahon]

On Thu, 12 Oct 2023 16:47:28 GMT, Daniel Fuchs <dfuchs at openjdk.org> wrote:

>> Some of the ThrowingSubscriberXxx tests (typically those that use a streaming body) have been observed failing intermittently (though rarely) in timeout. The error message printed at the end showed that some HTTP/2 stream subscribers had not been properly deregistered when an exception was thrown in GET_BODY.
>> 
>> The issue appears to be a race condition between `cancelImpl` and `schedule` where the scheduler `sched` may get stopped before the subscriber is exceptionally completed.
>> 
>> A simple fix is to ensure that `cancelImpl` will complete the subscriber, if needed.
>
> Daniel Fuchs has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Simplify the fix

Seems straight forward. LGTM

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Marked as reviewed by michaelm (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/16144#pullrequestreview-1676597872