Deadlock in operating systems occurs when two or more processes are
unable to proceed because each is waiting for the other to release a
resource, such as a lock or a semaphore. Here’s an explanation of deadlock
and an example:
### Explanation:
Deadlock occurs in a multitasking environment where multiple processes
compete for a finite set of resources. Deadlocks typically involve four
conditions:
1. **Mutual Exclusion**: Resources cannot be shared. Only one process can
use a resource at a time.
2. **Hold and Wait**: Processes hold resources while waiting for others.
3. **No Preemption**: Resources cannot be forcibly taken from a process.
They can only be released voluntarily.
4. **Circular Wait**: A cycle exists in the resource allocation graph, where
each process waits for a resource held by another process in the cycle.
### Example:
Consider a scenario with two processes, P1 and P2, and two resources, R1
and R2. Each process needs access to both resources to complete its task.
The following sequence of events can lead to a deadlock:
1. Process P1 acquires resource R1.
2. Process P2 acquires resource R2.
3. Process P1 requests access to resource R2 but is blocked because P2 holds
it.
4. Process P2 requests access to resource R1 but is blocked because P1 holds
it.
