CHAP6 - Concurrency Deadlock and Starvation Chapter 6...

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Concurrency: Deadlock and Starvation Chapter 6
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Deadlock Permanent blocking of a set of processes that either compete for system resources or communicate with each other No efficient solution Involve conflicting needs for resources by two or more processes
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Reusable Resources Used by one process at a time and not depleted by that use Processes obtain resources that they later release for reuse by other processes Processors, I/O channels, main and secondary memory, files, databases, and semaphores Deadlock occurs if each process holds one resource and requests the other
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Example of Deadlock
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Another Example of Deadlock Space is available for allocation of 200K bytes, and the following sequence of events occur Deadlock occurs if both processes progress to their second request P1 . . . . . . Request 80K bytes; Request 60K bytes; P2 . . . . . . Request 70K bytes; Request 80K bytes;
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Consumable Resources Created (produced) and destroyed (consumed) by a process Interrupts, signals, messages, and information in I/O buffers Deadlock may occur if a Receive message is blocking May take a rare combination of events to cause deadlock
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Example of Deadlock Deadlock occurs if receive is blocking P1 . . . . . . Receive(P2); Send(P2, M1); P2 . . . . . . Receive(P1); Send(P1, M2);
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Resource-Allocation Graph V is partitioned into two types: P = { P 1 , P 2 , …, P n }, the set consisting of all the processes in the system. R
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This note was uploaded on 07/25/2008 for the course CSE 410 taught by Professor Bonakdarpour during the Summer '08 term at Michigan State University.

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CHAP6 - Concurrency Deadlock and Starvation Chapter 6...

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