费时的操作 meaning in English

time-consuming operation

If a listener is going to perform a potentially time - consuming operation like processing a large document or doing something that may block , such as performing socket io , it should arrange to do that work in another thread so it can return to its caller quickly
如果侦听器要执行一个可能比较费时的操作，例如处理大型文本，或者要做的工作可能阻塞，例如执行socket io ，那么侦听器应当把这些操作安排在另一个线程中进行，这样它就可以迅速返回它的调用者。