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List:       openjdk-serviceability-dev
Subject:    Integrated: 8306446: java/lang/management/ThreadMXBean/Locks.java transient failures
From:       Kevin Walls <kevinw () openjdk ! org>
Date:       2023-07-28 9:49:28
Message-ID: 7_yFzyd-8zwObILEC7Ji1SuArvblCzXXwDY4ANsyVOg=.08d344ab-5a16-4af5-935d-3da837e7309b () github ! com
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On Thu, 15 Jun 2023 20:34:53 GMT, Kevin Walls <kevinw@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).

This pull request has now been integrated.

Changeset: 4ae5a3e3
Author:    Kevin Walls <kevinw@openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/4ae5a3e39b681bfd001df1483d8a6d1fce0bc7f8
                
Stats:     54 lines in 1 file changed: 31 ins; 1 del; 22 mod

8306446: java/lang/management/ThreadMXBean/Locks.java transient failures

Reviewed-by: cjplummer, sspitsyn

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

PR: https://git.openjdk.org/jdk/pull/14501


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