presto-main/src/main/java/io/prestosql/execution/MemoryRevokingScheduler.java/MemoryRevokingScheduler/requestMemoryRevokingIfNeeded
class MemoryRevokingScheduler:    @VisibleForTesting
    void requestMemoryRevokingIfNeeded()
    {
        if (checkPending.compareAndSet(false, true)) {
            runMemoryRevoking();
        }
    }