Deadlock Characterization in Operating System:

Deadlock occurs if the following four conditions take place simultaneously in a system:

1. Mutual Exclusion:

At least one resource must be held in a non-sharable mode. It means that only one process at a time can use the resource. If another process requests the resource, the requesting process must be delayed until the resource has been released.

2. Hold and Wait:

A process must be holding at least one resource and waiting, to acquire additional resources that are currently being held by other processes.

3. No Preemption:

Resources cannot be preempted. A resource can be released only voluntarily by the process holding it after that process has completed its task.

4. Circular Wait:

A set {P₀ P₁, P₂... P_n} of waiting processes must exist such that P₁ is waiting for a resource that is held by P₁, P₁ is waiting for a resource that is held by P₂, ..., P_n-1 is waiting for a resource that is held by P_n and P_n is waiting for a resource that is held by P₀.

All four conditions must hold for a deadlock to occur.

Relevant Articles: Introduction to Deadlocks Resources in Operating System Methods for Handling Deadlocks Deadlock Avoidance in Operating System Deadlock Characterization in Operating System Deadlock Detection/Algorithm/Example in Operating System Deadlock Recovery/Methods/Algorithms in Operating System