RFR: 8303916: ThreadLists.java inconsistent results

[Kevin Walls]

On Wed, 14 Jun 2023 09:30:49 GMT, Kevin Walls <kevinw at openjdk.org> wrote:

> This test fails when additional threads are created, as it compares thread lists from different sources and sees a mismatch.
> 
> It needs to tolerate some threads with certain names appearing, e.g. JVMCI and ForkJoin threads.  If there are extra threads in the thread ID list from the ThreadMBean, remove them from the thread count before comparing.
> 
> When it fails, additionally print the ids and names of threads that it got from the MBean.
> 
> I found the test quite confusing, the naming of thread counts, arrays of threads, and arrays of thread stacktraces from different sources, so have renamed some things.

> 

Thanks - that's a useful reference list.  For this test, it's never managed to not have Common-Cleaner in the initial set of threads it observes, I think...  But it's very easy to see a couple of ForkJoinPool-x-worker-x threads, and see one more of them by the time it gets threads from the MXBean.  That's the way I see it failing for us now.  If we do see others appear, I hope having added the extra printing it will be easy to add other names, if they affect this test...

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PR Comment: https://git.openjdk.org/jdk/pull/14465#issuecomment-1591874809