On Wed, 27 Mar 2024 02:57:40 GMT, Serguei Spitsyn <sspit...@openjdk.org> wrote:
>> This PR fixes a synchronization issue in the test:
>> `test/hotspot/jtreg/serviceability/jvmti/vthread/PopFrameTest`
>>
>> The method `notifyAtBreakpoint()` can notify the `TestTask` thread when it
>> has not reached an expected breakpoint yet.
>> The fix is to add a call to the method `ensureAtBreakpoint()` one more time
>> in the `B2` sub-test. It is needed after the top-most frame was popped with
>> the JVMTI `PopFrame`, and the target thread needs to reach the breakpoint
>> again after its execution was resumed.
>>
>> The time is very intermittent. At least, I was not able to reproduce the
>> timeout failure in thousands of mach5 runs with the `-Xcomp` option.
>>
>> Testing:
>> - Run the test
>> `test/hotspot/jtreg/serviceability/jvmti/vthread/PopFrameTest` thousands
>> times in mach5
>
> Serguei Spitsyn 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 three additional
> commits since the last revision:
>
> - “Merge”
> - review: updated test with one more call to notifyAtBreakpoint to reset the
> native state
> - 8328665: serviceability/jvmti/vthread/PopFrameTest failed with a timeout
test/hotspot/jtreg/serviceability/jvmti/vthread/PopFrameTest/PopFrameTest.java
line 147:
> 145: }
> 146: log("Main #B.2: got expected JVMTI_ERROR_NONE");
> 147: notifyAtBreakpoint(); // needed to reset the native state
This doesn't make much sense to me. The purpose of `notifyAtBreakpoint()` is
to unblock the Breakpoint event handler, which is waiting for this notify.
However, the event handler can only ever be entered once, yet we have a
previous `noitfyBreakpoint()` above and a 3rd `notifyAtBreakpoint()` below. It
seems that this call and the one below are no-ops. I don't see how
bp_sync_reached ever gets set true again after the first `notifyAtBreakpoint()`
call is made.
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/18419#discussion_r1540476191
