在多道程序系统中，虽然是可以借助多个进程的并发执行来改善系统的资源利用率来提高系统的吞吐量，但可能发生死锁。所以死锁是指多个进程在运行中因争夺资源而造成的一种僵局，当进程处于这种僵局状态是，若无外力作用，它们都将无法再向前推进。-In the multi-channel programming system, although they can take advantage of the concurrent execution of multiple processes to improve the system resource utilization to improve the system throughput, but the deadlock may occur. So, the deadlock is the result of multiple processes running in the competition for resources has led to a deadlock, when the process is in this deadlock, the absence of external force, they will no longer be able to move forward.