Suggestion needed to port the fix to JDK17 and JDK11

[Alan Bateman]

On 12/02/2025 06:13, Shruthi . wrote:
> We discussed the issue with AIX OS team to get their input as this 
> issue is happening only in AIX platform. Update from AIX OS dev team: 
> A thread gets stuck in dup2() while duplicating a file descriptor that 
> is already being used by two other threads (one for reading, one for 
> writing). The writer thread does not write or close the FIFO, causing 
> the reader to wait indefinitely, which blocks dup2(). Also he is 
> saying that we cannot change OS side as it may break or change its 
> existing behavior which other existing applications may be depending on.
>
> Can we apply the previously proposed fix at java level(reordering the 
> |preClose||()| method) while adding an AIX-specific check to ensure it 
> doesn’t affect other platforms? Or do you have any alternative 
> suggestions?
>
>           if (!tryClose()) {
>                 long th = thread;
>                 if (th != 0) {
>                     if (!AIX.isAIX)
>                         nd.preClose(fd);
>                     NativeThread.signal(th);
>                     if (AIX.isAIX)
>                         nd.preClose(fd);
>                 }
>             }

Are you sure this really fixes the issue on AIX? It means a reader or 
writer may be signalled before the syscall, is the signal missed or are 
you saying that it queues up on AIX? If it missed then the close will 
block in dup2 as before.

-Alan
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