8317801: java/net/Socket/asyncClose/Race.java fails intermittently (aix)

[shruacha1234]

This pull request contains a backport of commit 8f121a17 from the openjdk/jdk repository.
OpenJDK bug : https://bugs.openjdk.org/browse/JDK-8317801

This fix resolves a race condition in socket close handling that led to intermittent failures in Race.java on AIX in JDK17u-dev

The original patch didn’t apply cleanly to the JDK17u-dev branch due to differences in the NIO dispatcher implementation:

• UnixDispatcher introduced in later JDK versions does not exist in JDK17.
• Virtual thread related logic in the original patch is not present in JDK17.
• The dispatcher hierarchy differs slightly.

To adapt the change for JDK17:

• NativeDispatcher.preClose was updated to accept the reader and writer thread IDs.
• Thread signalling logic was moved into FileDispatcherImpl.
• Channel implementations (SocketChannelImpl, DatagramChannelImpl, ServerSocketChannelImpl, etc.) were updated to delegate signalling through the dispatcher rather than performing it locally.

These changes preserve the functional intent of the upstream patch, ensuring that threads blocked in I/O operations are correctly signalled when a file descriptor is pre-closed.

Testing : local AIX build, java_io, java_nio, jdk_net
Additionally, executed java/net/Socket/asyncClose/Race.java 500 times to check for intermittent failures. No failures were observed.

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Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• JDK-8317801 needs maintainer approval
• Commit message must refer to an issue

Issue

• JDK-8317801: java/net/Socket/asyncClose/Race.java fails intermittently (aix) (Bug - P4)

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[openjdk]

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See the Progress checklist in the description for automated requirements.

[openjdk]

This backport pull request has now been updated with issue from the original commit.

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