8297424: java/net/httpclient/AsyncExecutorShutdown.java fails in AssertionError due to misplaced assert

[dfuch]

The ResponseSubscribers.HttpResponseInputStream class has an assert that has been observed firing (rarely) when running the java/net/httpclient/AsyncExecutorShutdown.java test.

After a thorough analysis of the code and the log failure I am convinced that the issue is due to a misplaced assert.
If cancellation happens asynchronously while the subscriber is being subscribed with the lower layers of the stack, the HttpResponseInputStream might get closed and the LAST_LIST buffer might be offered after closed == false has been observed by the onSubscribed method, but before the assertion has been checked. The assertion assumes that the queue must be empty, but it might not if close has been called and the LAST_LIST buffer has been offered.

Moving the assert from within the synchronized block, to ensure that the observed value of closed is consistent with the state of the queue, should fix it. I have tagged the bug as noreg-hard, I'm not sure it would be fair to say that AsyncExecutorShutdown.java can be used to verify the fix.

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Issue

• JDK-8297424: java/net/httpclient/AsyncExecutorShutdown.java fails in AssertionError due to misplaced assert

Reviewers

• Jaikiran Pai (@jaikiran - Reviewer)

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[jaikiran]

Hello Daniel, the change where we move the assert into the synchronized block looks fine to me. Looking at the code I think the check to see that the buffers can accomodate at least 2 elements (when onSubscribe is called) looks correct to me because the buffers will be initialized in the constructor of HttpResponseInputStream with a capacity of at least 2. So the assert itself looks correct.

This PR also has changes in the Stream class. Some of those changes are typo related fixes, so that's fine. However, it also has other functional changes. Is that intentional and related?

[dfuch]

This PR also has changes in the Stream class. Some of those changes are typo related fixes, so that's fine. However, it also has other functional changes. Is that intentional and related?

These are changes I made when investigating the fix, and they are not related. The pendingResponseSubscriber is a temporary field that holds the subscriber value until the responseSubscriber is handled and subscribed by the schedule loop. It is a bit confusing to see a non null pendingResponseSubscriber after it has been handled by that loop. Practically, setting it to null or leaving it assigned at this point should have no effect on the behavior of this class... Hmmm... except I see ternary operators that first look at the subscriber and then at the pending subscriber. So this change now introduce a potential race condition if they are executed concurrently with the schedule loop. Good observation. I will revert that.

[jaikiran]

Thank you Daniel. The latest changes look good to me.

[openjdk]

@dfuch This change now passes all automated pre-integration checks.

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After integration, the commit message for the final commit will be:

8297424: java/net/httpclient/AsyncExecutorShutdown.java fails in AssertionError due to misplaced assert

Reviewed-by: jpai

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At the time when this comment was updated there had been 9 new commits pushed to the master branch:

• 4e8e853: 6788481: CellEditorListener.editingCanceled is never called
• 692bedb: 8297106: Remove the -Xcheck:jni local reference capacity checking
• 05128c2: 8286185: The Java manpage can be more platform inclusive
• d450314: 8297276: Remove thread text from Subject.current
• cdf9ed0: 8297528: java/io/File/TempDirDoesNotExist.java test failing on windows-x64
• 105d9d7: 8295351: java/lang/Float/Binary16Conversion.java fails with "Unexpected result of converting"
• a80552e: 8236919: Refactor com.sun.tools.javac.main.CommandLine into a reusable module for other JDK tools
• a249a52: 8296754: AutoCreateSharedArchive in JDK 20 is not compatible with JDK 19
• 405b188: 8297570: jdk/jfr/threading/TestDeepVirtualStackTrace.java fails with -XX:-UseTLAB

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[dfuch]

/integrate

[openjdk]

Going to push as commit 5d2772a.
Since your change was applied there have been 17 commits pushed to the master branch:

• 361b50e: 8292594: Use CSS custom properties for all fonts and colors
• 42b60ed: 8297030: Reduce Default Keep-Alive Timeout Value for httpclient
• 1301fb0: 8296470: Refactor VMError::report STEP macro to improve readability
• 48017b1: 8296804: Document HttpClient configuration properties in java.net.http module-info
• bd51b7e: 8296645: org.openjdk.bench.javax.tools.Javac leaves class files in current directory
• b27a61e: 8297216: Search results omit some methods
• 33dfc7d: 8296954: G1: Enable parallel scanning for heap region remset
• 6f06f44: 8297242: Use-after-free during library unloading on Linux
• 4e8e853: 6788481: CellEditorListener.editingCanceled is never called
• 692bedb: 8297106: Remove the -Xcheck:jni local reference capacity checking
• ... and 7 more: https://git.openjdk.org/jdk/compare/ba0a2521ba6d7db041580be7cda633311836b455...master

Your commit was automatically rebased without conflicts.

[openjdk]

@dfuch Pushed as commit 5d2772a.

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