Identifying deadlocks in system state
Deadlock detection involves periodically examining the system state to determine whether a deadlock has occurred. This approach doesn't try to prevent deadlocks but instead detects them after they happen and then takes recovery actions. Detection algorithms maintain a resource allocation graph or wait-for graph that represents processes and resources and their relationships. For systems with single instances of each resource type, deadlock can be detected by looking for cycles in the wait-for graph. For systems with multiple instances of resource types, detection algorithms similar to the Banker's Algorithm are used but without the safe state concept - instead they look for processes that cannot complete given current resource availability. The detection algorithm must be run periodically, and the frequency involves a trade-off between detection latency and computational overhead. Once a deadlock is detected, the system can employ recovery strategies such as process termination or resource preemption. Deadlock detection is suitable for systems where deadlocks are rare or where prevention/avoidance techniques are too restrictive. It provides better resource utilization than prevention but requires recovery mechanisms and periodic overhead for running detection algorithms.