jmx-dev RFR: 8020875 java/lang/management/ThreadMXBean/ResetPeakThreadCount.java fails intermittently

[David Holmes]

On 24/07/2013 7:31 PM, Mandy Chung wrote:
>
> On 7/24/2013 4:50 PM, shanliang wrote:
>> So we have 2 kinds of issues here:
>> 1) the test related, like Thread state checking, we can fix them in
>> the test
>> 2) MBean.getThreadCount() issue, we can create a bug to trace it (add
>> your test case to the bug), and add a workaround (sleep or call 2
>> times) in the test to make the test pass. Mandy is the expert and
>> better to get her opinion.
>
> It's probably a race in the VM implementation in determining the thread
> count.   You will need to diagnose the VM implementation and compare the
> thread list and the implementation of getting the thread count (check
> hotspot/src/share/vm/services/threadService.cpp)

There is a considerable code path between the point where a terminating 
thread causes Thread.join() to be allowed to return, and the point where 
the live thread count gets decremented. So using join() does not help 
here. Arguably JVMTI should have based its counts around the lifecycle 
of the Java thread not the underlying native thread.

David
-----

> Mandy