Deadlock Recovery

• Abort all deadlock processes and release resource - too drastic - will lead to loss of work.
• Abort one process at a time - releasing resources until no deadlockHow do we determine which process to abort first ? - priority ordering, process which has done least work.
• Selectively restart processes from a previous checkpoint i.e. before it claimed any resources difficult to achieve - sometimes impossible.
• Successively withdraw resources from a process and give to another process until deadlock is broken. How to choose which processes and which resources ?

1. Complex decisions due to the large number of processes present within a system.
2. Difficult to automate.
3. Use Operator to resolve conflicts - BUT this requires the operator to have skill and understanding of what processes are actually doing.