[jdk17] RFR: 8269865: Async UL needs to handle ERANGE on exceeding SEM_VALUE_MAX [v3]

[Xin Liu]

On Tue, 6 Jul 2021 22:09:13 GMT, Xin Liu <xliu at openjdk.org> wrote:

>> This patch solved the sempahore overflow issue with errno ERANGE or EOVERFLOW.
>> Previously, we have asymmetric p/v operations for semaphore _sem. Each iteration
>> only decrements _sem 1 but dequeues N messages. If logging threads keep preempting
>> async logging thread, it may cause the value of _sem accumulates until overflow! 
>> 
>> The patch corrects the value of _sem after write(). n messages are dequeued/processed.
>> We need to invoke _sem.wait() max(n-1, 1) time. This ensures that each iteration
>> decrements n instead of 1.
>
> Xin Liu has updated the pull request incrementally with three additional commits since the last revision:
> 
>  - Ignore sem_post failure when _sem of AsyncLogWriter is overflown.
>  - Revert "8269865: Async UL needs to handle ERANGE on exceeding SEM_VALUE_MAX"
>    
>    This reverts commit 269a1580990fa955c1f9d37ce1d04a6349959992.
>  - Revert "Fix build issue on Windows and simplify the loop."
>    
>    This reverts commit e385f42fa4e03510242039518281077e3c9897cf.

got it. I will cover Windows.

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PR: https://git.openjdk.java.net/jdk17/pull/216