[jdk17] RFR: 8269865: Async UL needs to handle ERANGE on exceeding SEM_VALUE_MAX [v4]

[Thomas Stuefe]

On Wed, 7 Jul 2021 08:08:10 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 one additional commit since the last revision:
> 
>   Use the new API signal_overflow of semaphore
>   
>   This patch handles overflow scenerios for Posix and Windows.
>   MacOS platform doesn't have any error so we ignore it.

Sorry for dropping out, I'm snowed in. I put the patch into our AIX CI. Due to the slowness of our AIX hardware, this may take a day or two.

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