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

[Robbin Ehn]

On Wed, 11 Nov 2020 22:43:49 GMT, Daniel D. Daugherty <dcubed 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.
> 
> Perhaps:
> // If we need to load any classes do execute doSleep(), do it now.

Fixed

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