Snapshot Algorithms Chandy-Mishra Ho-Ramammorthy 2 phase

Index Introduction Experimental Setup Results Analysis Conclusion Future Work References

Introduction Snapshot Algorithm: One phase snapshots Two phase snapshots Chandy Mishra: Any random process can take snapshot at random time Snapshot consists of state information about the system and message queue Ho-Ramammorthy: Status Table maintained by each process Coordinator process creates WFG’s from status table

Experimental Setup Snapshot algorithms run on top of a basic algorithm. In this implementation Basic algorithm used is simple flooding. Each process forwards a message at least once. Each process receives at least one message. When above two conditions are satisfied algorithm terminates. Data points are inserted to count total number of messages forwarded and total Time taken.

Results Analysis: Chandy Mishra Output Process process2: taking snapshot Process process4 has : Process process3 has : Message3 Process process2 has : Process process1 has : Process process0 has : SimulationEngine MessageQueue has :Message0,Message1,Message2 MessageDispatcher : Message0 from process1 to Processes process3 Process process3: taking snapshot Process process4 has : Process process3 has : Message0 Process process2 has : Process process1 has : Process process0 has : SimulationEngine MessageQueue has :Message1,Message2,Message3 MessageDispatcher : Message1 from process1 to Processes process2 MessageDispatcher : Message2 from process2 to Processes process1 Process process0: taking snapshot Process process4 has : Process process3 has : Process process2 has : Process process1 has : Message2 Process process0 has : SimulationEngine MessageQueue has :Message3,Message0,Message1

Results Analysis: Ho-Ramammorthy Output process3 : selectedProcess :process4 process4 : selectedProcess :process1 process0 : selectedProcess :process3 process1 : selectedProcess :process4 process4 : selectedProcess :process3 process0 : selectedProcess :process1 process4 is locked by Message1 and waiting for process3 process3 is locked by Message0 and waiting for process4 process2 is not locked by any message process1 is locked by Message2 and waiting for process4 process0 is locked by Message3 and waiting for process1 In createWFGAndDetectDealLock Deadlock Detected process4 is locked by Message1 and waiting for process3 process3 is locked by Message0 and waiting for process4 process2 is not locked by any message process1 is locked by Message2 and waiting for process4 process0 is locked by Message3 and waiting for process1 In createWFGAndDetectDealLock Deadlock Detected Deadlock detected: process4-->process3-->process4

Results analysis: Ho-Ramammorthy

Result Analysis : Ho-Ramammorthy

Result Analysis: Chandy Mishra

Message Complexity Comparison: Number of Nodes Messages

Time Complexity Comparison: Number Of Processes Time

Conclusion As seen in the graphs performance of Ho-Ramammorthy 2 phase snapshot algorithm is better than Chandy Mishra snapshot algorithm. Message Complexity of Ho-Ramammorthy 2 phase snapshot is better than Chandy Mishra snapshot algorithm. Time complexity of Ho-Ramammorthy 2 phase deadlock detection is better than Chandy Mishra snapshot algorithm. Possibility of false deadlock detection in Ho-Ramammorthy 2 phase snapshot algorithm remains in the implementation.

Future Work Implementing the algorithms in more scalable manner. Algorithm implementations needs to be tested on large real distributed systems. Ho-Ramammorthy 2 phase snapshot algorithm implementation can be improved to reduce/remove the false deadlock detection possibility.

References: Distributed Deadlock Detection-K Mani Chandy and Jaydev Mishra CHANDY, K.M., AND MISRA, J. A distributed algorithm for detecting resource deadlocks in distributed systems. In Proc. A CM SIGA CT-SIGOPS Syrup. Principles of Distributed Computing (Ottawa, Canada, August 18-20, 1982), ACM, New York, 1982, pp LAMPORT, L. Time, clocks, and the ordering of events in a distributed system. Commun. ACM 21, 7 (July 1978),