The bigger problem with the synchronized Collections wrappers, and the earlier Hashtable and Vector classes, is that they synchronize on a single lock.

同步的集合包装器以及早期的Hashtable和Vector类带来的更大的问题是，它们在单个的锁上进行同步。

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They heard how mathematicians have found that the urge to synchronize works inside flocks of birds, schools of fish and certain inorganic objects.

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