Serial and Parallel Garbage Collectors now ensure that no Java threads are in a JNI critical region before initiating a GC. Previously, GC could early-return from a safepoint if any thread remained in such a region, delaying collection. With this change, a pending GC request will wait for all Java threads to exit JNI critical regions and block new entries, guaranteeing that once inside the safepoint, no threads remain in critical regions and GC can proceed to completion. As a result, the diagnostic flag `GCLockerRetryAllocationCount` has been removed, as it is no longer necessary.