This document discusses circular wait deadlocks, which occur when multiple processes are waiting for resources held by each other in a circular chain, such that Process A is waiting for a resource held by Process B, Process B is waiting for a resource held by Process C, and so on until the chain loops back to Process A waiting for a resource held by the first process. The document outlines four conditions for deadlocks, including circular wait, and provides examples of how acquiring locks simultaneously could prevent a circular wait deadlock from occurring.

1. Operating Systems by Muhammad Umair
Circular Wait
Inherited from Deadlock Conditions

2. Deadlock Visual Concept
Is it a state where two ore more operations are
waiting for each other, say a computing action
'A' is waiting for action 'B' to complete, while
action 'B' can only execute when 'A' is completed.

3. Cont..
• A deadlock happens in this case if Thread1 and
Thread2 are running simultaneously, and Thread1
acquires lock A and Thread2 acquires lock B. Then,
they both need the lock that the other thread has to
proceed. No advancement.
One way to deal with a case like this would be to
make a function which would grab two locks for a
thread simultaneously, instead of one at a time.

4. Circular wait
It only happens when there is
a processes which are waiting
for other resources to finish.

5. 4 Reasons of Deadlock
1: Mutual Exclusion
2 : Hold and Wait
3 : No Primitive
4 : Circular wait
Circular wait - Each process is waiting
to obtain a resource which is held by
another process.

6. • Thank
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