RFR: 8305913: com/sun/jdi/JdbLastErrorTest.java failed with "'lastError = 42' missing from stdout/stderr" [v2]

[Kevin Walls]

On Sat, 15 Apr 2023 10:15:20 GMT, Kevin Walls <kevinw at openjdk.org> wrote:

>> This test is failing often since 8304725 added a call to Thread::current_in_asgct().  This can end up being called e.g. when resolving calls, and then the OS last error value is lost.
>> 
>> The test is reliable with a single warm-up call to getLastError.invoke() before the loop.
>> 
>> The test was introduced when in JDK-8292302 a change was undone that had made JavaThread::threadObj call Thread::current_or_null_safe, as the use of TLS upset this case of accessing last error directly.
>> 
>> This new Thread::current_in_asgct() case shows that the VM will find new ways to interfere with the last error value, or at least new VM code keeps wanting to call Thread::current.  This testcase is kind of niche usage, so it not an argument that VM code should not be calling Thread::current.   If this test is to stay active, it needs to have this warm-up getLastError call.  (If there are more issues, it might mean removing the test.)
>
> Kevin Walls has updated the pull request incrementally with one additional commit since the last revision:
> 
>   comment update feedback

Thanks for looking at this, and for the Panama pointer to JDK-8294970 - I'm checking if that completely solves it for this testcase...

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PR Comment: https://git.openjdk.org/jdk/pull/13481#issuecomment-1525338902