Demonstration on Unblocking Checkpoint for Fault-Tolerance in Pregel-Like Systems

Pregel-like systems are developed to execute iterative applications on massive graph data, which often leads to a long runtime. These systems are usually deployed on a cluster of commodity servers, where failures are common. Hence, fault-tolerance is crucial for them. A typical fault-tolerance technique is checkpointing, which can be achieved in a blocking or an unblocking manner. Blocking checkpointing incurs notable overhead as it pauses iterative computation. Unblocking checkpointing decrease the overhead by parallelizing checkpointing and iterative computation. However, it introduces resource contention due to parallel checkpointing tasks, which may prolong overall execution time. The queuing strategy and the staleness/tardiness-aware skipping policy can effectively improve unblocking checkpointing by alleviating the resource contention and selecting an optimal checkpoint from the queued checkpoints, respectively. In this demonstration, we showcase their internal mechanisms based on Apache Giraph.