RFR: 8247972: incorrect implementation of JVM TI GetObjectMonitorUsage [v12]
Serguei Spitsyn
sspitsyn at openjdk.org
Mon Feb 19 15:33:23 UTC 2024
> The implementation of the JVM TI `GetObjectMonitorUsage` does not match the spec.
> The function returns the following structure:
>
>
> typedef struct {
> jthread owner;
> jint entry_count;
> jint waiter_count;
> jthread* waiters;
> jint notify_waiter_count;
> jthread* notify_waiters;
> } jvmtiMonitorUsage;
>
>
> The following four fields are defined this way:
>
> waiter_count [jint] The number of threads waiting to own this monitor
> waiters [jthread*] The waiter_count waiting threads
> notify_waiter_count [jint] The number of threads waiting to be notified by this monitor
> notify_waiters [jthread*] The notify_waiter_count threads waiting to be notified
>
> The `waiters` has to include all threads waiting to enter the monitor or to re-enter it in `Object.wait()`.
> The implementation also includes the threads waiting to be notified in `Object.wait()` which is wrong.
> The `notify_waiters` has to include all threads waiting to be notified in `Object.wait()`.
> The implementation also includes the threads waiting to re-enter the monitor in `Object.wait()` which is wrong.
> This update makes it right.
>
> The implementation of the JDWP command `ObjectReference.MonitorInfo (5)` is based on the JVM TI `GetObjectMonitorInfo()`. This update has a tweak to keep the existing behavior of this command.
>
> The follwoing JVMTI vmTestbase tests are fixed to adopt to the `GetObjectMonitorUsage()` correct behavior:
>
> jvmti/GetObjectMonitorUsage/objmonusage001
> jvmti/GetObjectMonitorUsage/objmonusage003
>
>
> The following JVMTI JCK tests have to be fixed to adopt to correct behavior:
>
> vm/jvmti/GetObjectMonitorUsage/gomu001/gomu00101/gomu00101.html
> vm/jvmti/GetObjectMonitorUsage/gomu001/gomu00101/gomu00101a.html
> vm/jvmti/GetObjectMonitorUsage/gomu001/gomu00102/gomu00102.html
> vm/jvmti/GetObjectMonitorUsage/gomu001/gomu00102/gomu00102a.html
>
>
>
> A JCK bug will be filed and the tests have to be added into the JCK problem list located in the closed repository.
>
> Also, please see and review the related CSR:
> [8324677](https://bugs.openjdk.org/browse/JDK-8324677): incorrect implementation of JVM TI GetObjectMonitorUsage
>
> The Release-Note is:
> [8325314](https://bugs.openjdk.org/browse/JDK-8325314): Release Note: incorrect implementation of JVM TI GetObjectMonitorUsage
>
> Testing:
> - tested with mach5 tiers 1-6
Serguei Spitsyn has updated the pull request incrementally with one additional commit since the last revision:
review: addressed comments from David
-------------
Changes:
- all: https://git.openjdk.org/jdk/pull/17680/files
- new: https://git.openjdk.org/jdk/pull/17680/files/63706e51..81b7787b
Webrevs:
- full: https://webrevs.openjdk.org/?repo=jdk&pr=17680&range=11
- incr: https://webrevs.openjdk.org/?repo=jdk&pr=17680&range=10-11
Stats: 12 lines in 1 file changed: 8 ins; 4 del; 0 mod
Patch: https://git.openjdk.org/jdk/pull/17680.diff
Fetch: git fetch https://git.openjdk.org/jdk.git pull/17680/head:pull/17680
PR: https://git.openjdk.org/jdk/pull/17680
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