Unsafe State in Resource-Allocation Graph

· The RAG above is compose of 2 resources and 2 processes
· P1 holds an instance of R1
· P2 is requesting an instance of R1
· P2 holds an instance of R2
· P1 may request an instance of R2

Resource-Allocation Graph For Deadlock Avoidance

· The Resource Allocation Graph (RAG) above is composed of 2 processes and 2 resources.
· P1 holds an instance of R1
· P2 requests an instance of R1
· P1 and P2 may request an instance of R2

Resource-Allocation Graph With A Cycle But No Deadlock

• P1 is holding an instance of R2 and requests instance of R1.
• P2 is holding an instance of of R1.
• P3 is holding an instance of R1 and requests instance of R2.
• P4 is holding instance of R2.

Resource-Allocation Graph With A Deadlock

• P1 is holding an instance of R2 and requests instance of R2 and requests instance of R1
• P2 is holding an instance of R1 and R2 then requests of instance of R3
• P3 is holding an instance of R3 and requests an instance of R2
• R1 or resource 1 is composed of only one instance
• R2 has 2 instances
  
• R3 has one instance
  
• R4 has 3 instances

Example of Resource-Allocation Graph

• P1 is holding an instance of R2 and requests instance of R1.
  
• P2 is holdng an instsnce of R1 and R2 ang requests of instance of R3.
  
• P3 is holding an instance of R3.