Operating System

Deadlock CharacterizationDeadlock can arise if four conditions hold simultaneously:
• Mutual exclusion: only one process at a time can use a resource
• Hold and wait: a process holding at least one resource is waiting to acquire additional resources held by other processes
• No preemption: a resource can be released only voluntarily by the process holding it, after that process has completed its task
• Circular wait: there exists a set {P0, P1, …, Pn, P0} of waiting processes such that
– P0 is waiting for a resource that is held by P1,
– P1 is waiting for a resource that is held by P2,
– …,
– Pn–1 is waiting for a resource that is held by Pn,
– and Pn is waiting for a resource that is held by P0.