等待线

• However , under heavy contention , performance will suffer dramatically , as the jvm spends more time dealing with scheduling threads and managing contention and queues of waiting threads and less time doing real work , like incrementing counters
  然而，在竞争激烈时，这将大大损害性能，因为jvm用了更多的时间来调度线程，管理竞争和等待线程队列，而实际工作（如增加计数器）的时间却很少。