On Wed, 21 Jun 2023 12:33:46 GMT, Andrey Turbanov <aturba...@openjdk.org> wrote:
>> This test iterates an array of ThreadInfos in a few places (e.g. in the
>> method doCheck()), and needs to tolerate and ignore nulls, in case a thread
>> finishes and the test hits an NPE.
>>
>> There are other calls like "TM.getThreadInfo(tid).getLockName()" which might
>> often be risky, but if the threads are blocked as they are here, they can't
>> be terminating, so this usage is safe.
>>
>>
>> The test has additional problems when started in a virtual thread.
>> ThreadMXBean.getThreadInfo() methods only return a ThreadInfo for platform
>> threads. The test needs to avoid some checks if mainThread is virtual.
>>
>> In assertNoLock, it needs to not object to a thread holding a lock on a
>> VirtualThread object is not relevant.
>> Also the loop in doChecks which follows a chain of locks... This needs to
>> recognise that ForkJoinPool thead is not worth pursuing. It's not one of
>> the very narrow set of threads this test cares about.
>>
>> Despite these exclusions, the test does some reasonable verification work
>> when MainThread is virtual. This test historically cam in with a general
>> "JVM monitoring and management API" change, it is not testing a particular
>> fix.
>>
>>
>> There's a failure condition in doCheck() which will not make the test fail:
>> if it logs "TEST FAILED" in its final for loop, there is no failure. Make
>> the loop count the failures, and throw if there are any.
>>
>> Also, while looking into this... The variable names in some methods are
>> confusing. In checkBlockedObject(), let's use "threadName" rather than
>> "result" if we are finding a thread name, and let's not reuse the same
>> result variable for a lockName later in the method.
>>
>> The logs from this test are hard to read and verify, I find it better if the
>> lock objects OBJB and OBJC are of classes other than Object, so you get to
>> read, e.g.:
>> LockAThread blocked on Locks$ObjectB@4691fdfd
>> (ObjectB, not just Object).
>
> test/jdk/java/lang/management/ThreadMXBean/Locks.java line 72:
>
>> 70: .filter(Objects::nonNull)
>> 71: .filter(i ->
>> name.equals(i.getLockOwnerName()))
>> 72: .filter(i ->
>> !i.getLockName().contains("java.lang.VirtualThread"))
>
> Suggestion:
>
> .filter(i ->
> !i.getLockName().contains("java.lang.VirtualThread"))
ThreadMXBean::getAllThreadsIds returns an array of the thread IDs of platform
threads, it doesn't include virtual threads, so I don't know why this filter is
added.
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/14501#discussion_r1236933317
