[SysD] Fail Fast

What

Immediately reports at its interface any condition that is likely to indicate a failure.

Why

Are usually designed to stop normal operation rather than attempt to continue a possibly flawed process. 

How

check the system's state at several points in an operation, so any failures can be detected early. 

The responsibility of a fail-fast module is detecting errors, then letting the next-highest level of the system handle them.

Java ex

ail-fast 机制是Java集合(Collection)中的一种错误机制。 在用迭代器遍历一个集合对象时，如果遍历过程中对集合对象的结构进行了修改（增加、删除），则会抛出Concurrent Modification Exception（并发修改异常）。