![GROUP: MARS
2
Humayra Khanum [161-15-7325]
Rezwana Islam Ria [161-15-7071]](https://image.slidesharecdn.com/osdeadlockf-180906092746/85/Deadloack-Operating-System-2-320.jpg)
Deadloack-Operating System
- 1. BYTHE NAME OFALLAH Presented To- Ms. Mahbuba Maliha Mourin Lecturer,Dept Of CSE Daffodil International University
- 2. GROUP: MARS 2 Humayra Khanum [161-15-7325] Rezwana Islam Ria [161-15-7071]
- 4. WHATIS DEADLOCK? o An example from US Kansas law: o “When two trains approach each other at a crossing, both shall come to a full stop and neither shall start up again until the other has gone.” 44
- 6. Deadlock in Operating System A DEADLOCK is a situation in which two process is sharing the same resource and preventing each other from accessing the resource, resulting in case where both process is not working. Example 6
- 7. Four Conditions Of deadlock Mutual Exclusion At least on resource of the system is in non-sharable mode, that is only one process may use it at any given time. Thus if any other process requests for the resource, then that process will have to wait until the current process which is using the resource release it. Hold and Wait A process must exist which is already holding a resource and also waiting to grab one or more resources which are currently being held by another processes. No preemption Resources can not be preempted, that is, a resource can be released only by the process that is currently holding it, voluntarily. Thus, release of the process is out of control and a process may hold a resource forever. Circular Wait There must exist a set of processes; such as, p0,p1,p2….pN; which are waiting for resources which are in hold by other processes. The process that p0 need is in hold by p1, the process that p1 need is in hold by p2 and so on. It is a dead-end. 7
- 8. DEADLOCK PREVENTION Eliminate one (or more) of: mutual exclusion hold and wait no preemption (i.e. have preemption) circular wait 8
- 9. Name : Rezwana Islam Ria ID: 161-15-7071
- 10. Banker’s Algorithm Deadlock avoidance algorithm. It’s less efficient than resource allocation graph algorithm. But it is applicable to resource allocation system with multiple instances of each resource type. 1 0
- 11. In this algorithm there are following matrices: 1.N number of processes 2. m number of resources. .Calculate safe sequence is if possible . 1 1
- 15. Wait For Graph Create a wait for graph by removing the resource type nodes from a resource allocation graph Deadlock exists if and only if the wait-for graph contains a cycle. 1 5
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- 17. 281 7