唯有在存取集合之前，将所有执行绪都锁定物件，同步处理才会有效。

Synchronization is effective only if all threads lock the object before accessing the collection.

youdao

此方法的默认实现需要由派生类重写，以便在清除集合之前执行某些操作。

The default implementation of this method is intended to be overridden by a derived class to perform some action before the collection is cleared.

youdao

如果在时间运行完之前需求团队确实找到了足够充分的集合，在这种情况下，他们总是继续发明更多的需求而不是声明任务已经完成。

In cases where the requirements team actually finds a sufficient set before the time runs out, they invariably go on to invent more requirements rather than declare the task complete.

youdao

And that does two things: bug one, it helps catch bugs in your code, and secondly it often converts it into a more efficient sequence of instructions before you actually go off and run it. All right?

这有两点好处：,第一是可以帮助你发现程序中的，第二是把你的代码,在运行之前,转换为更有效率的指令的集合，对不对？

麻省理工公开课 - 计算机科学及编程导论课程节选