RFR: 8247972: incorrect implementation of JVM TI GetObjectMonitorUsage [v23]

[Serguei Spitsyn]

On Mon, 11 Mar 2024 18:44:34 GMT, Daniel D. Daugherty <dcubed at openjdk.org> wrote:

>> Serguei Spitsyn has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 26 commits:
>> 
>>  - Merge
>>  - review: minor tweak in test description of ObjectMonitorUsage.java
>>  - review: addressed more comments on the fix and new test
>>  - rename after merge: jvmti_common.h to jvmti_common.hpp
>>  - Merge
>>  - review: update comment in threads.hpp
>>  - fix deadlock with carrier threads starvation in ObjectMonitorUsage test
>>  - resolve merge conflict for deleted file objmonusage003.cpp
>>  - fix a typo in libObjectMonitorUsage.cpp
>>  - fix potential sync gap in the test ObjectMonitorUsage
>>  - ... and 16 more: https://git.openjdk.org/jdk/compare/de428daf...b97b8205
>
> test/hotspot/jtreg/serviceability/jvmti/ObjectMonitorUsage/libObjectMonitorUsage.cpp line 215:
> 
>> 213:   if (tested_monitor != nullptr) {
>> 214:     jni->DeleteGlobalRef(tested_monitor);
>> 215:   }
> 
> Since this is at the beginning of `setTestedMonitor` does it mean that we "leak"
> the last global ref?

Thank you for the check. There is no leak of the last global ref because there is always this call at the end of each sub-test: `setTestedMonitor(null)`.

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PR Review Comment: https://git.openjdk.org/jdk/pull/17680#discussion_r1520733090