6941395: G1: Use only lock-free versions of region stack push() and pop() Summary: Re-enable use of the lock-free versions of region stack push() and pop() by recording aborted regions in a thread-local structure, which are then processed when scanning of the region stack restarts. The previous locking versions of these routines are retained for diagnostic purposes. Reviewed-by: tonyp, ysr

6983296: build sanity checks for jdk7 should require SS12u1 Reviewed-by: ohair

6984287: Regularize how GC parallel workers are specified. Summary: Associate number of GC workers with the workgang as opposed to the task. Reviewed-by: johnc, ysr