8317801: java/net/Socket/asyncClose/Race.java fails intermittently (aix) by shruacha1234 · Pull Request #4294 · openjdk/jdk17u-dev

shruacha1234 · 2026-03-15T14:48:27Z

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.

Progress

Change must not contain extraneous whitespace
JDK-8317801 needs maintainer approval
Commit message must refer to an issue
Change must be properly reviewed (2 reviews required, with at least 2 Reviewers)

Issue

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

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$ git fetch https://git.openjdk.org/jdk17u-dev.git pull/4294/head:pull/4294
$ git checkout pull/4294

Update a local copy of the PR:
$ git checkout pull/4294
$ git pull https://git.openjdk.org/jdk17u-dev.git pull/4294/head

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$ git pr checkout 4294

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https://git.openjdk.org/jdk17u-dev/pull/4294.diff

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Signed-off-by: Shruthi <Shruthi.Shruthi1@ibm.com>

bridgekeeper · 2026-03-15T14:49:12Z

👋 Welcome back sacharya! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

openjdk · 2026-03-15T14:49:15Z

❗ This change is not yet ready to be integrated.
See the Progress checklist in the description for automated requirements.

openjdk · 2026-03-15T14:49:29Z

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

mlbridge · 2026-03-15T14:53:24Z

Webrevs

jerboaa · 2026-03-16T14:24:15Z

This backport is being done very differently in JDK 17u because for JDK 21u the following dependencies where included first in the JDK 21 release before doing the actual backport for this bug:

8294399: (ch) Refactor some methods out of sun.nio.ch.UnixFileDispatcherImpl => https://bugs.openjdk.org/browse/JDK-8294399
8351458: (ch) Move preClose to UnixDispatcher => https://bugs.openjdk.org/browse/JDK-8351458

It would have helped if this information was provided to the reader. If we end up going this route without the enhancement backports (which should be fine IMO), then we should more accurately model it to pre-existing JDK 17u code. A review follows shortly.

jerboaa · 2026-03-16T14:25:45Z

src/java.base/unix/classes/sun/nio/ch/DatagramDispatcher.java

+        FileDispatcherImpl dispatcher = new FileDispatcherImpl();
+        dispatcher.preClose(fd, reader, writer);


This should just delegate to FileDispatcherImpl as before:

Suggested change

FileDispatcherImpl dispatcher = new FileDispatcherImpl();

dispatcher.preClose(fd, reader, writer);

FileDispatcherImpl.preClose(fd, reader, writer);

In order to avoid the name clash with the non-static variant use a name other than preClose. E.g. doPreClose

src/java.base/unix/classes/sun/nio/ch/FileDispatcherImpl.java

src/java.base/unix/classes/sun/nio/ch/SocketDispatcher.java

jerboaa · 2026-03-16T14:33:59Z

/reviewers 2 Reviewer

openjdk · 2026-03-16T14:35:57Z

@jerboaa
The total number of required reviews for this PR (including the jcheck configuration and the last /reviewers command) is now set to 2 (with at least 2 Reviewers).

Signed-off-by: Shruthi <Shruthi.Shruthi1@ibm.com>

jerboaa

The build failure should be resolved in a different way (rename the shared static method).

jerboaa · 2026-03-17T09:43:59Z

src/java.base/unix/classes/sun/nio/ch/FileDispatcherImpl.java

    }

-    void implPreClose(FileDescriptor fd, long reader, long writer) throws IOException {
+    static void implPreClose(FileDescriptor fd, long reader, long writer) throws IOException {


Make it private, please. Or fold it into doPreClose

jerboaa · 2026-03-17T09:51:02Z

src/java.base/unix/classes/sun/nio/ch/FileDispatcherImpl.java

     * dup'ed to a special fd and the thread signalled so that the syscall fails with EINTR.
     */
-    final void preClose(FileDescriptor fd, long reader, long writer) throws IOException {
+    static final void preClose(FileDescriptor fd, long reader, long writer) throws IOException {


static void doPreClose(...)

Also, please add a comment similar to the the one that was added in preClose0 (and remove the one for preClose0 as it's now outdated:

// Shared with SocketDispatcher and DatagramDispatcher

preClose0 is only used in this class now, so should be private.

jerboaa · 2026-03-17T10:03:19Z

src/java.base/unix/classes/sun/nio/ch/DatagramDispatcher.java

+        FileDispatcherImpl dispatcher = new FileDispatcherImpl();
+        dispatcher.preClose(fd, reader, writer);


In order to avoid the name clash with the non-static variant use a name other than preClose. E.g. doPreClose

Backport 8f121a173ca2534c706682f6c68fbbb0b94ec057

9024d1c

Signed-off-by: Shruthi <Shruthi.Shruthi1@ibm.com>

openjdk bot changed the title ~~Backport 8f121a173ca2534c706682f6c68fbbb0b94ec057~~ 8317801: java/net/Socket/asyncClose/Race.java fails intermittently (aix) Mar 15, 2026

openjdk bot added backport Port of a pull request already in a different code base rfr Pull request is ready for review labels Mar 15, 2026

jerboaa reviewed Mar 16, 2026

View reviewed changes

shruacha1234 added 2 commits March 16, 2026 22:59

Addressing the review comments

b17b6bc

Signed-off-by: Shruthi <Shruthi.Shruthi1@ibm.com>

Addressing the build failure

8d5361e

Signed-off-by: Shruthi <Shruthi.Shruthi1@ibm.com>

jerboaa suggested changes Mar 17, 2026

View reviewed changes

		FileDispatcherImpl dispatcher = new FileDispatcherImpl();
		dispatcher.preClose(fd, reader, writer);

	FileDispatcherImpl dispatcher = new FileDispatcherImpl();
	dispatcher.preClose(fd, reader, writer);
	FileDispatcherImpl.preClose(fd, reader, writer);

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shruacha1234 commented Mar 15, 2026 •

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