Performs completion action if triggered, returning a dependent that may need propagation, if one exists.
Returns true if possibly still triggerable. Used by cleanStack.
Possibly blocks the current thread, for example waiting for a lock or condition.
Returns {@code true} if blocking is unnecessary. @return {@code true} if blocking is unnecessary
Completion for recording and releasing a waiting thread. This class implements ManagedBlocker to avoid starvation when blocking actions pile up in ForkJoinPools.