Deadlock: A situation in which two or more processes are unable to proceed because each is waiting for one the others to do something.
For example, consider two processes, P1 and P2, and two resources, R1 and R2. Suppose that each process needs access to both resources to perform part of its function. Then it is possible to have the following situation: the OS assigns R1 to P2, and R2 to P1. Each process is waiting for one of the two resources. Neither will release the resource that it already owns until it has acquired the other resource and performed the function requiring both resources. The two processes are deadlocked
Livelock: A situation in which two or more processes continuously change their states in response to changes in the other process(es) without doing any useful work:
For example , consider two processes each waiting for a resource the other has but waiting in a non-blocking manner. When each learns they cannot continue they release their held resource and sleep for some times, then they retrieve their original resource followed by trying to the resource the other process held, then left, then reacquired. Since both processes are trying to cope (just badly), this is a livelock.
Starvation: A situation in which a runnable process is overlooked indefinitely by the scheduler; although it is able to proceed, it is never chosen.
For example , consider three processes (P1, P2, P3) each require periodic access to resource R. Consider the situation in which P1 is in possession of the resource, and both P2 and P3 are delayed, waiting for that resource. When P1 exits its critical section, either P2 or P3 should be allowed access to R. Assume that the OS grants access to P3 and that P1 again requires access before P3 completes its critical section. If the OS grants access to P1 after P3 has finished, and subsequently alternately grants access to P1 and P3, then P2 may indefinitely be denied access to the resource, even though there is no deadlock situation.
For example, consider two processes, P1 and P2, and two resources, R1 and R2. Suppose that each process needs access to both resources to perform part of its function. Then it is possible to have the following situation: the OS assigns R1 to P2, and R2 to P1. Each process is waiting for one of the two resources. Neither will release the resource that it already owns until it has acquired the other resource and performed the function requiring both resources. The two processes are deadlocked
Livelock: A situation in which two or more processes continuously change their states in response to changes in the other process(es) without doing any useful work:
For example , consider two processes each waiting for a resource the other has but waiting in a non-blocking manner. When each learns they cannot continue they release their held resource and sleep for some times, then they retrieve their original resource followed by trying to the resource the other process held, then left, then reacquired. Since both processes are trying to cope (just badly), this is a livelock.
Starvation: A situation in which a runnable process is overlooked indefinitely by the scheduler; although it is able to proceed, it is never chosen.
For example , consider three processes (P1, P2, P3) each require periodic access to resource R. Consider the situation in which P1 is in possession of the resource, and both P2 and P3 are delayed, waiting for that resource. When P1 exits its critical section, either P2 or P3 should be allowed access to R. Assume that the OS grants access to P3 and that P1 again requires access before P3 completes its critical section. If the OS grants access to P1 after P3 has finished, and subsequently alternately grants access to P1 and P3, then P2 may indefinitely be denied access to the resource, even though there is no deadlock situation.
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