Anurag Agarwal
ABSTRACT
In a concurrent system with N processes, vector clocks of size N are used for tracking dependencies between the events. Using vectors of size N leads to scalability problems. Moreover, association of components with processes makes vector clocks cumbersome and inefficient for systems with a dynamic number of processes. We present a class of logical clock algorithms, called chain clock, for tracking dependencies between relevant events based on generalizing a process to any chain in the computation poset. Chain clocks are generally able to track dependencies using fewer than N components and also adapt automatically to systems with dynamic number of processes. We compared the performance of Dynamic Chain Clock (DCC) with vector clock for multithreaded programs in Java. With 1% of total events being relevant events, DCC requires 10 times fewer components than vector clock and the timestamp traces are smaller by a factor of 100. Although DCC requires shared data structures, it is still 10 times faster than vector clock in our experiments.
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Index Terms
- Efficient dependency tracking for relevant events in shared-memory systems
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