A possible method for preventing deadlocks is to have a single, higher$-$order resource that must be requested before any other resource. For example, if multiple threads attempt to access the synchronization objects A $$ E$,$ deadlock is possible. $($Such synchronization objects may include mutexes, semaphores, condition variables, and the like.$)$ We can prevent deadlock by adding a sixth object F$.$ Whenever a thread wants to acquire the synchronization lock for any object A $$ E$,$ it must first acquire the lock for object F$.$ This solution is known as containment: the locks for objects A $$ E are contained within the lock for object F$.$

Compare this scheme with the circular$-$wait scheme of Section $8\mathrm{.}5\mathrm{.}4($of Text book$).$