RFR: 8231585: java/lang/management/ThreadMXBean/MaxDepthForThreadInfoTest.java fails with java.lang.NullPointerException

[David Holmes]

Hi Daniil,

On 18/04/2020 6:03 am, Daniil Titov wrote:
> Please review the change that fixes intermittent failure of java/lang/management/ThreadMXBean/MaxDepthForThreadInfoTest.java
> 
> As David noticed (thank you, David, for this analysis) there is no guarantee that all threads found by getAllThreadIds() are still alive by the time we call getThreadInfo() so we have to allow for null array entries.
> 
> Testing:  Mach5 tests with Graal on passed 300 times.

Fix looks good - thanks.

I think it would be informative to actually determine which thread(s) is 
disappearing (not as part of the test just as some diagnostic info to 
add to the JBS issue). Can you reproduce the failure easily?

Thanks,
David

> [1] http://cr.openjdk.java.net/~dtitov/8231585/webrev.01/
> [2] https://bugs.openjdk.java.net/browse/JDK-8231585
> 
> Best regards,
> Daniil
> 
>