RFR: 8244679: JVM/TI GetCurrentContendedMonitor/contmon001 failed due to "(IsSameObject#3) unexpected monitor object: 0x000000562336DBA8"

[Patricio Chilano Mateo]

On Wed, 11 Nov 2020 20:33:15 GMT, Robbin Ehn <rehn at openjdk.org> wrote:

> As the stack trace in the bug shows, we cannot load classes, since we may take a monitor.
> Resulting in an unexpected result to GetCurrentContendedMonitor().
> Trying to use some decent primitive, e.g. Wicket/Semaphore/.., without being implementation dependent means we must warm up every possible scenario, since it may use a new class.
> Instead I here just use sleep + volatile for the barriers.
> 
> I cannot reproduce with these changes.
> 
> Chewing through T6 as most issues have been seen there.

test/hotspot/jtreg/vmTestbase/nsk/jvmti/GetCurrentContendedMonitor/contmon001.java line 67:

> 65:     public static int run(String argv[], PrintStream ref) {
> 66:         out = ref;
> 67:         doSleep(); // If it would do any class loading, do it now.

I think now the spawned thread should not try to resolve any new methods after setting the boolean so we shouldn't have the same ObjectLocker issue.

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

PR: https://git.openjdk.java.net/jdk/pull/1177