[15] RFR(S): 8247967: SparkExamples24H.java SIGSEGV in various places

[David Holmes]

H Markus,

On 24/06/2020 12:32 am, Markus Gronlund wrote:
> Greetings,
> 
> Please review the following change set to correct the improper thread transition introduced as part of JDK-8245113.
> 
> Bug: https://bugs.openjdk.java.net/browse/JDK-8247967
> Webrev: http://cr.openjdk.java.net/~mgronlun/8247967/webrev00/
> Testing: jdk_jfr
> 
> Thanks to David Holmes for pinpointing this embarrassing issue.

I'm glad to see a simple use of the existing transition helper was 
possible here. The fix looks good.

One minor note:

443       DEBUG_ONLY(JfrJavaSupport::check_java_thread_in_native(thread));
  444       // can safepoint here
  445       ThreadInVMfromNative transition((JavaThread*)thread);

ThreadInVMfromNative will also assert that the thread is actually in native.

Thanks,
David

> Thanks
> Markus
>