RFR: 8369515: Deadlock between JVMTI and JNI ReleasePrimitiveArrayCritical [v2]

[Fredrik Bredberg]

On Thu, 18 Dec 2025 01:21:17 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> As discussed in JBS the deadlock occurs when the call to `ReleasePrimitiveArrayCritical` performs the transition from native to VM, and in the process checks for special runtime exit conditions - which includes the `obj_deopt_suspend` request. The simple solution is to define a custom JNI ENTRY with custom `ThreadInVMfromNative` that elides the exit check.
>> 
>> The change is limited to `ReleasePrimitiveArrayCritical` and `ReleaseStringCritical`.
>> 
>> UPDATE: we are now employing a much simpler solution.
>> 
>> There is no regression test as this has only been seen in long running stress tests.
>> 
>> Testing:
>>    -tiers 1-6
>
> David Holmes has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains four additional commits since the last revision:
> 
>  - Greatly simplifed fix to just defer object_deopt whilst in JNI critical region
>  - Merge branch 'master' into 8369515-jni-critical
>  - Revert "8369515"
>    
>    This reverts commit 3beb23ccbf5adb98d8c6ad404d40c603bbf499dc.
>  - 8369515

Fixing deadlock issues caused by suspend requests can easily become quite messy, but not this time. I think it's an elegant solution, with a good explaining source code comment. Thank you!

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Marked as reviewed by fbredberg (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/28779#pullrequestreview-3591638468