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List:       openjdk-serviceability-dev
Subject:    Re: RFR: 8308429: jvmti/StopThread/stopthrd007 failed with "NoClassDefFoundError: Could not initiali
From:       Alan Bateman <alanb () openjdk ! org>
Date:       2023-09-30 9:26:50
Message-ID: -UED75ZhURs9lB-nT-KjlKeZ7CyiUYGCd9rv30jflhM=.4d0b970f-7844-4f37-a4c0-351d59bc9959 () github ! com
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On Thu, 28 Sep 2023 21:04:58 GMT, Leonid Mesnik <lmesnik@openjdk.org> wrote:

> > The test fails because ThreadDeath is raised during class \
> > jdk.internal.misc.VirtualThreads initialization. The proposed fix is to \
> > pre-initialize this step to avoid such failures. See more details in the bug. I \
> > reproduced the original problem and verified that it is not reproduced after fix. \
> >  Tested with tier5 and running nsk/jvmti tests with and without virtual test \
> > thread factory. 
> > I don't think that more complex fix is needed. There is a plan to review \
> >                 nsk/jvmti stopThread tests and see if 
> > ./serviceability/jvmti/vthread/StopThreadTest/StopThreadTest.java 
> > might be improved to cover them.
> 
> Leonid Mesnik has updated the pull request incrementally with one additional commit \
> since the last revision: 
> missed import added.

One other general comment is that "stop" has been removed from the user-facing APIs \
for several releases. The use-case for JVMTI StopThread (and the JDWP/JDI \
equivalents) is mostly the debugger scenario where a thread is at a breakpoint and \
the developer wants to test how the code behaves when an exception is thrown, e.g. \
ask the debugger to throw IllegalArgumentException or SQLException at this point. \
This is a bit more controlled than shooting an arrow at the executing code as that \
leads to very unpredictable behavior. So I guess my point is that there may be merit \
is "degrading" StopThread to only require that it be supported when the target thread \
is suspended at an event. This would align it where we got to with virtual threads.  \
There may also be merit is re-examining the tests that are sending async exceptions \
as sending the terminally deprecated ThreadDeath is troublesome, it may be better to \
have tests for StopThread focus on cases where the target thread is suspended at an   \
event.

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

PR Comment: https://git.openjdk.org/jdk/pull/15966#issuecomment-1741723936


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