This presentation discusses deadlock in operating systems, defining it as a scenario where two or more processes cannot proceed because each is waiting for a resource held by the other. It outlines the necessary conditions for deadlock, including mutual exclusion, hold and wait, no preemption, and circular wait, along with strategies for prevention, avoidance, and recovery. Key techniques mentioned include the Banker's algorithm and methods for terminating processes or rolling them back to a safe state.

1. Deadlock in Operating
Systems
This presentation explores the critical concept of deadlock within
operating systems.

2. What is Deadlock?
Definition
A deadlock occurs when two or more processes are
blocked, each waiting for a resource held by another
process.
Example
Scenario: Process A holds a printer and waits for a scanner,
while Process B holds the scanner and waits for the printer.
Result: Neither process can proceed, leading to a deadlock
as both are waiting indefinitely for resources held by the
other.

3. Necessary Conditions for Deadlock
1 Mutual Exclusion
Only one process can access a
resource at a time.
2 Hold and Wait
A process holding a resource can
request another resource held
by another process.
3 No Preemption
Resources can't be forcibly taken
from a process holding it.
4 Circular Wait
A circular chain of processes exists, where each process waits for a resource held by the next process in the chain.

4. Deadlock Prevention
Prevent Mutual
Exclusion
Share resources, but this may
not be feasible for all
resources.
Prevent Hold and Wait
A process must request all
resources it needs upfront.
Prevent No Preemption
Allow resources to be taken
away from processes if
necessary.
Prevent Circular Wait
Establish a linear order for
resource requests.

5. Deadlock Avoidance
Resource Allocation Graph
A graphical representation of processes and resources to
detect potential deadlocks.
Banker's Algorithm
A resource allocation algorithm that ensures safe states by
preventing deadlocks from occurring.

6. Deadlock Recovery
1 Process Termination
Terminate processes involved in the deadlock.
2 Resource Preemption
Take away resources from processes involved in the deadlock.
3 Rollback
Restore processes to a previous safe state and restart them.