On Tue, 23 Jul 2024 06:58:33 GMT, Serguei Spitsyn <sspit...@openjdk.org> wrote:
> The test
> `serviceability/jvmti/GetOwnedMonitorInfo/GetOwnedMonitorInfoTest.java` is
> failing with the assert in the `thaw_internal()` function. The assert is not
> fully correct as it does not account for an unexpected scenario.
>
> Thanks to Patricio for reproducing this failure and identifying the root
> cause:
>> The problem is that we can unmount a virtual thread, then mount it again,
>> thaw a few frames, execute code that acquires a JNI monitor, and then call
>> thaw again without releasing that monitor. In this test this will happen if
>> the vthread is unmounted in System.out.println("Thread doing JNI call: "
>> ...) because of contention with the main thread doing
>> System.out.println("Main waiting for event.").
> The issue can be reproduced by adding Thread.yield() before
> jniMonitorEnterAndLetObjectDie().
>
> The fix corrects the assert to account for the `thread->jni_monitor_count()`.
> Question: Is the same scenario possible for non-JNI monitors as well?
> Also, the fix includes the test tweak described above which makes this
> failure always reproducible.
>
> Testing:
> - Ran the test `GetOwnedMonitorInfoTest.java` locally
> - Mach5 tiers 1-6 are passed
This pull request has now been integrated.
Changeset: d3e51daf
Author: Serguei Spitsyn <sspit...@openjdk.org>
URL:
https://git.openjdk.org/jdk/commit/d3e51daf7331b84b4e78f7f10360848d7c549c1a
Stats: 7 lines in 2 files changed: 3 ins; 0 del; 4 mod
8334085: Test crash: assert(thread->held_monitor_count() == 0) failed: Must be
Reviewed-by: dholmes, pchilanomate
-------------
PR: https://git.openjdk.org/jdk/pull/20294
