8290732: JNI DestroyJavaVM can start shutdown when one non-daemon thread remains #9803

dholmes-ora · 2022-08-09T06:10:40Z

Please review this fix for a problem discovered by @stuart-marks in the course of examining the VM shutdown behaviour. The VM code assumed that only unattached threads called JNI's DestroyJavaVM and so they were always attached as non-daemon threads. But it is perfectly valid to call DestroyJavaVM from an already attached thread, which could be a daemon. The fix simply checks whether the caller is a daemon or not and adjusts the expected count of active threads to see. There is also an adjustment to the thread termination logic to also notify at the right time.

Thanks to @stuart-marks for the reproducer in JBS - the longest part of this by many hours was converting the test over the jtreg. :)

Testing:

the new test on all core platforms
tiers 1-3
Thanks.

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JDK-8290732: JNI DestroyJavaVM can start shutdown when one non-daemon thread remains

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Thomas Stuefe (@tstuefe - Reviewer)
Robbin Ehn (@robehn - Reviewer)

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…ead remains

bridgekeeper · 2022-08-09T06:12:11Z

👋 Welcome back dholmes! 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 · 2022-08-09T06:15:03Z

@dholmes-ora The following labels will be automatically applied to this pull request:

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mlbridge · 2022-08-09T06:17:58Z

Webrevs

tstuefe

Hi David,

that was interesting. I always thought you have to detach before destroying the VM.

I looked into https://docs.oracle.com/javase/7/docs/technotes/guides/jni/spec/invocation.html and it says:

"Detaching from the VM: A native thread attached to the VM must call DetachCurrentThread() to detach itself before exiting."

Cheers, Thomas

test/hotspot/jtreg/runtime/jni/daemonDestroy/Main.java

test/hotspot/jtreg/runtime/jni/daemonDestroy/TestDaemonDestroy.java

tstuefe · 2022-08-09T09:26:44Z

test/hotspot/jtreg/runtime/jni/daemonDestroy/TestDaemonDestroy.java

+ * @build Main
+ * @run main/native TestDaemonDestroy
+ * @run main/native TestDaemonDestroy daemon
+ */


If you do two @test sections, you can give them speaking names(e.g. @test id=demon) and they can run in parallel.

I didn't think that was warranted/necessary here.

I disagree. Splitting the test leads causes better runtime (on my 24 core machine: 10.5 seconds vs 16 seconds). It also makes the jtr file easier to read, since it only contains one test. It also is simpler to run a selected test if you want to reproduce an error.

It is regrettable that splitting the test section causes too much duplication. Maybe we could improve the jtreg syntax in the future.

But you also have to duplicate the build instructions and building takes longer than execution on my systems (7 seconds versus 5) so if I had to pay for machine time I'd actually be worse off now!

Oh, you are right. That's unfortunate.

make/test/JtregNativeHotspot.gmk

dholmes-ora · 2022-08-11T02:53:19Z

Thanks for looking at this @tstuefe and @magicus

stuart-marks · 2022-08-11T04:03:32Z

Thanks for fixing this. I'm glad my reproducer gave you a good start, but you had to do all the grunt work of error checking and jtreg conversion. :-) Things look reasonable to me, but I'm not too familiar with this code and with Hotspot testing, so I'll defer to other reviewers.

tstuefe

Looks good.

openjdk · 2022-08-11T10:05:38Z

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

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

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

8290732: JNI DestroyJavaVM can start shutdown when one non-daemon thread remains

Reviewed-by: stuefe, rehn

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 63 new commits pushed to the master branch:

083e014: 8292233: Increase symtab hash table size
45e5b31: 8292244: Remove unnecessary include directories
9bfffa0: 8291945: Add OSInfo API for static OS information
bd58553: 8290833: Remove ConstantPoolCache::walk_entries_for_initialization()
755ecf6: 8292153: x86: Represent Registers as values
dedc05c: 8291640: java/beans/XMLDecoder/8028054/Task.java should use the 3-arg Class.forName
3d20a8b: 8291959: FileFontStrike#initNative does not properly initialize IG Table on Windows
a28ab7b: 8288568: Reduce runtime of java.security microbenchmarks
7ea9ba1: 8292064: Convert java/lang/management/MemoryMXBean shell tests to java version
fc1d94e: 8292232: AIX build failure by JDK-8290840
... and 53 more: https://git.openjdk.org/jdk/compare/8e2c006cd14905c06e8c2cc30f13de249d54ed79...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

tstuefe

Still good.

dholmes-ora · 2022-08-12T05:50:01Z

Thanks @tstuefe !

Can I get second review please.

robehn

Thanks!

dholmes-ora · 2022-08-12T06:40:09Z

Thanks @robehn !

/integrate

openjdk · 2022-08-12T06:41:32Z

Going to push as commit 6eb7c3a.
Since your change was applied there have been 63 commits pushed to the master branch:

083e014: 8292233: Increase symtab hash table size
45e5b31: 8292244: Remove unnecessary include directories
9bfffa0: 8291945: Add OSInfo API for static OS information
bd58553: 8290833: Remove ConstantPoolCache::walk_entries_for_initialization()
755ecf6: 8292153: x86: Represent Registers as values
dedc05c: 8291640: java/beans/XMLDecoder/8028054/Task.java should use the 3-arg Class.forName
3d20a8b: 8291959: FileFontStrike#initNative does not properly initialize IG Table on Windows
a28ab7b: 8288568: Reduce runtime of java.security microbenchmarks
7ea9ba1: 8292064: Convert java/lang/management/MemoryMXBean shell tests to java version
fc1d94e: 8292232: AIX build failure by JDK-8290840
... and 53 more: https://git.openjdk.org/jdk/compare/8e2c006cd14905c06e8c2cc30f13de249d54ed79...master

Your commit was automatically rebased without conflicts.

openjdk · 2022-08-12T06:41:43Z

@dholmes-ora Pushed as commit 6eb7c3a.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.

dholmes-ora added 2 commits August 9, 2022 01:56

8290732: JNI DestroyJavaVM can start shutdown when one non-daemon thr…

1c53be2

…ead remains

Remove commented out test code

f6479fa

openjdk bot added the rfr Pull request is ready for review label Aug 9, 2022

openjdk bot added hotspot-runtime hotspot-runtime-dev@openjdk.org build build-dev@openjdk.org labels Aug 9, 2022

tstuefe reviewed Aug 9, 2022

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make/test/JtregNativeHotspot.gmk Outdated Show resolved Hide resolved

dholmes-ora added 2 commits August 10, 2022 22:18

Address Thomas's feedback

ad58174

Fixed if block indentation per Magnus's request

ae30559

tstuefe approved these changes Aug 11, 2022

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openjdk bot added the ready Pull request is ready to be integrated label Aug 11, 2022

Suggestion from Thomas

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robehn approved these changes Aug 12, 2022

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dholmes-ora deleted the 8290732-destroyJavaVM branch August 12, 2022 06:47

8290732: JNI DestroyJavaVM can start shutdown when one non-daemon thread remains #9803

8290732: JNI DestroyJavaVM can start shutdown when one non-daemon thread remains #9803

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