On Thu, 15 Jun 2023 20:34:53 GMT, Kevin Walls <kev...@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 <kev...@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
