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A wait-for graph in computer science is a directed graph used for deadlock detection in operating systems and relational database systems.. In computer science, a system that allows concurrent operation of multiple processes and locking of resources and which does not provide mechanisms to avoid or prevent deadlock must support a mechanism to detect deadlocks and an algorithm for recovering ...
occurrence of deadlock in distributed system. P 1 initiates deadlock detection. C 1 sends the probe saying P 2 depends on P 3. Once the message is received by C 2, it checks whether P 3 is idle. P 3 is idle because it is locally dependent on P 4 and updates dependent 3 (2) to True. As above, C 2 sends probe to C 3 and C 3 sends probe to C 1.
In computer science, deadlock prevention algorithms are used in concurrent programming when multiple processes must acquire more than one shared resource.If two or more concurrent processes obtain multiple resources indiscriminately, a situation can occur where each process has a resource needed by another process.
Banker's algorithm is a resource allocation and deadlock avoidance algorithm developed by Edsger Dijkstra that tests for safety by simulating the allocation of predetermined maximum possible amounts of all resources, and then makes an "s-state" check to test for possible deadlock conditions for all other pending activities, before deciding whether allocation should be allowed to continue.
This approach may be used in dealing with deadlocks in concurrent programming if they are believed to be very rare and the cost of detection or prevention is high. A set of processes is deadlocked if each process in the set is waiting for an event that only another process in the set can cause.
In databases and transaction processing, two-phase locking (2PL) is a pessimistic concurrency control method that guarantees conflict-serializability. [1] [2] It is also the name of the resulting set of database transaction schedules (histories).
Semaphore locking also has a time limit to prevent a deadlock condition in which a lock is acquired by a single process for an infinite time, stalling the other processes that need to use the shared resource protected by the critical section.
In software engineering, a spinlock is a lock that causes a thread trying to acquire it to simply wait in a loop ("spin") while repeatedly checking whether the lock is available.