All the processes that are involved in the deadlock are terminated.After a deadlock is detected, it can be resolved using the following methods − This forms a circular wait loop.Ī deadlock can be detected by a resource scheduler as it keeps track of all the resources that are allocated to different processes. Similarly, Process 2 is allocated Resource 1 and it is requesting Resource 2. For example: Process 1 is allocated Resource2 and it is requesting Resource 1. It will only be released when Process 1 relinquishes it voluntarily after its execution is complete.Ī process is waiting for the resource held by the second process, which is waiting for the resource held by the third process and so on, till the last process is waiting for a resource held by the first process. In the diagram below, Process 2 cannot preempt Resource 1 from Process 1. A process can only release a resource voluntarily.
In the diagram given below, Process 2 holds Resource 2 and Resource 3 and is requesting the Resource 1 which is held by Process 1.Ī resource cannot be preempted from a process by force. In the diagram below, there is a single instance of Resource 1 and it is held by Process 1 only.Ī process can hold multiple resources and still request more resources from other processes which are holding them. There should be a resource that can only be held by one process at a time. The Coffman conditions are given as follows − But these conditions are not mutually exclusive. Coffman ConditionsĪ deadlock occurs if the four Coffman conditions hold true. Process 1 and process 2 are in deadlock as each of them needs the other’s resource to complete their execution but neither of them is willing to relinquish their resources. Similarly process 2 has resource 2 and needs to acquire resource 1. In the above diagram, the process 1 has resource 1 and needs to acquire resource 2. A deadlock happens in operating system when two or more processes need some resource to complete their execution that is held by the other process.
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