Deadlock Prevention<\/h3>\n
To prevent a deadlock before it occurs the system checks every transaction before execution. This way if there is even a small chance for deadlock to occur, a process is not allowed to execute.<\/p>\n
Deadlock Avoidance<\/h3>\n
Deadlock avoidance is better than deadlock prevention. As once the deadlock occurs additional information is required, like how the OS should use resources. Thus, deadlock avoidance is a simple and useful model in which each process declares the amount and type of resources that it may need.<\/p>\n
Coffman Conditions<\/h3>\n
For a deadlock to occur following four Coffman conditions need to hold true.<\/p>\n
1. Mutual Exclusion:<\/strong> Mutex (Mutual Exclusion) is a type of binary semaphore that helps control access to the shared resources. It also has a priority inheritance mechanism that avoids extended priority inversion problems and allows tasks with higher priority to execute first. Shared resources don\u2019t lead to deadlocks, but resources, like printers and tape drives, need exclusive access.<\/p>\n 2. Hold and Wait:<\/strong> Processes hold one or more resources all the while waiting for the one they have requested.<\/p>\n 3. Circular Wait:<\/strong> When a process waits for a resource held by another process, which is also waiting for a resource held by a third process, and so on, a circular chain is created. This ordeal is known as circular wait. It forms a circular loop where it is necessary that every process requests resources in increasing order of enumeration.<\/p>\n For example, Process A has Resource B but it needs Resource A and requests it. Similarly, another process, Process B has Resource A but it is requesting Resource B. This situation creates a circular wait loop.<\/p>\n![\"OS](\"https:\/\/data-flair.training\/blogs\/wp-content\/uploads\/sites\/2\/2021\/08\/OS-DEADLOCK-normal-image01.jpg\")
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