A general repeated snapshot algorithm

Snapshot algorithms are fundamental for many distributed applications. This paper presents a repeated snapshot algorithm for non-FIFO asynchronous distributed systems. The algorithm attaches numbers of snapshot to messages, uses token passing and needs little space on each process. Its message complexity of control messages for one snapshot is O(n). Using this algorithm, processes can get consistent global states at their convenience concurrently. The algorithm is proved. The availability of the algorithm is discussed.