Circular Wait - aryanjoshi0823/5143-Operating-System GitHub Wiki

Circular Wait in Operating Systems

Circular Wait is one of the necessary conditions for a deadlock to occur in a system. It refers to a situation where a group of processes is waiting on each other in a circular chain, such that each process holds at least one resource and is waiting to acquire a resource held by the next process in the chain.

Example:

  • Process P1 holds Resource R1 and waits for R_2.
  • Process P2 holds Resource R_2 and waits for R_1.

This circular dependency prevents any process from proceeding, leading to a deadlock.

Preventing Circular Wait:

To prevent circular wait and avoid deadlock, one or more of the following strategies can be employed:

  1. Impose a Resource Ordering:

    • Assign a unique number to each resource type.
    • Require processes to request resources in increasing numerical order.

  2. Break the Circle:

    • Use algorithms that detect and resolve circular dependencies (e.g., Banker's Algorithm).
    • Introduce a timeout or resource preemption mechanism.

Circular wait is a critical concept in resource allocation and deadlock management in operating systems.