9deadlock - Deadlocks in Distributed Systems Deadlocks in...

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Deadlocks in Distributed Systems Deadlocks in distributed systems are similar to deadlocks in single processor systems, only worse. They are harder to avoid, prevent or even detect. They are hard to cure when tracked down because all relevant information is scattered over many machines. People sometimes might classify deadlock into the following types: Communication deadlocks -- competing with buffers for send/receive Resources deadlocks -- exclusive access on I/O devices, files, locks, and other resources. We treat everything as resources, there we only have resources deadlocks. Four best-known strategies to handle deadlocks: The ostrich algorithm (ignore the problem) Detection (let deadlocks occur, detect them, and try to recover) Prevention (statically make deadlocks structurally impossible) Avoidance (avoid deadlocks by allocating resources carefully)
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The FOUR Strategies for handling deadlocks The ostrich algorithm No dealing with the problem at all is as good and as popular in distributed systems as it is in single-processor systems. In distributed systems used for programming, office automation, process control, no system-wide deadlock mechanism is present -- distributed databases will implement their own if they need one. Deadlock detection and recovery is popular because prevention and avoidance are so difficult to implement. Deadlock prevention is possible because of the presence of atomic transactions. We will have two algorithms for this. Deadlock avoidance is never used in distributed system, in fact, it is not even used in single processor systems. The problem is that the banker’s algorithm need to know (in advance) how much of each resource every process will eventually need. This information is rarely, if ever, available. Hence, we will just talk about deadlock detection and deadlock prevention.
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Distributed Deadlock Detection Since preventing and avoiding deadlocks to happen is difficult, researchers works on detecting the occurrence of deadlocks in distributed system. The presence of atomic transaction in some distributed systems makes a
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This note was uploaded on 09/17/2009 for the course IT it771 taught by Professor Jenisha during the Fall '09 term at University of Advancing Technology.

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9deadlock - Deadlocks in Distributed Systems Deadlocks in...

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