RFR: 8145908: [Newtest] Multi-threading stress test for G1 Remembered Sets

[Dmitry Fazunenko]

Hello everyone,

Would you look at a new stress for G1 Remembered Sets, please.

http://cr.openjdk.java.net/~dfazunen/8145908/webrev.02/
https://bugs.openjdk.java.net/browse/JDK-8145908

The test allocates objects in several G1 heap regions and then creates 
and removes references to them from other regions in multiple threads,
causing Remembered Set to be updated.
The test doesn't make any assumptions about VM behavior, it just expects 
that VM will not crash.

Thanks,
Dima