RFR(M): 8230459: Test failed to resume JVMCI CompilerThread

[Doerr, Martin]

Hi,

after some discussions with David and Kim, I think we have a direction to go forward.

The discussion in the bug and on the mailing list is pretty long:
https://bugs.openjdk.java.net/browse/JDK-8230459
http://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2019-October/035462.html

To make long story short, I suggest to create new j.l.Thread objects only for JVMCI threads when (re)starting more threads on demand.
This avoids such issues with observable thread state transitions etc.

This is my current proposal:
http://cr.openjdk.java.net/~mdoerr/8230459_JVMCI_thread_objects/webrev.03/

Please review.

Best regard,
Martin