Integrated: 8247972: incorrect implementation of JVM TI GetObjectMonitorUsage

[Serguei Spitsyn]

On Fri, 2 Feb 2024 00:44:00 GMT, Serguei Spitsyn <sspitsyn at openjdk.org> wrote:

> 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

This pull request has now been integrated.

Changeset: b92440f9
Author:    Serguei Spitsyn <sspitsyn at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/b92440f9b1f41643bf9649ca192e405a9d6c026a
Stats:     1180 lines in 15 files changed: 741 ins; 390 del; 49 mod

8247972: incorrect implementation of JVM TI GetObjectMonitorUsage

Reviewed-by: dcubed, lmesnik

-------------

PR: https://git.openjdk.org/jdk/pull/17680