This is good practice, because the waiting time of the reader thread is reduced after wake-up.

这是一种好做法，因为这会减少唤醒之后读线程的等待时间。

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For instance, a thread waiting until items are added to a linked list may wake up to find the list empty.

比如，一个正在等待货物被加入到链表中的线程，当它被唤醒时可能发现链表是空的。

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Once the condition is met you need a method to wake up the thread (s) that are waiting for that particular condition to become true.

一旦条件满足，还需要一种方法以唤醒因等待满足特定条件而睡眠的线程。

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