The deadlock problem(死锁问题) A set of blocked processes each holding a resource and waiting to acquire a resource held by another process in the set (一组等待的进程,其中每一个进程都持有资源,并且等待着由 这个组中其他进程所持有的资源) ° Example(例如) System has2 tape drives.(系统有两个磁带设备) P, and P2 each hold one tape drive and each needs another one.(进程P1和P2各占有一个磁带设备并且实际需 要两个磁带) Example 为 hores A and B, initialized to1(信号量A,B初始化 sem wait(A); wait(B) wait (B); wait(A) Applied Operating System Concepts 8 Silberschatz, GalVin, and Gagne@1999Silberschatz ,Galvin, and Gagne©1999 8.2 Applied Operating System Concepts The Deadlock Problem（死锁问题） • A set of blocked processes each holding a resource and waiting to acquire a resource held by another process in the set. （一组等待的进程，其中每一个进程都持有资源，并且等待着由 这个组中其他进程所持有的资源） • Example （例如） – System has 2 tape drives.（系统有两个磁带设备） – P1 and P2 each hold one tape drive and each needs another one.（进程P1和P2各占有一个磁带设备并且实际需 要两个磁带） – Example – semaphores A and B, initialized to 1（信号量A，B初始化 为1） P0 P1 wait (A); wait(B) wait (B); wait(A)