Strongly consistent global state detection for on-line control of distributed applications

Abstract

Global states can be used for distributed/parallel application monitoring and control. Strongly consistent global states (SCGS) are especially well suited for on-line controlling. Existing SCGS detecting algorithms work with process local states. They must wait for state terminations before complete states can be taken into account. Because of that the global states seen by a monitor always belong to the past. We present an algorithm, which works with unterminated local states. This approach lets the monitor detect SCGS sooner: currently lasting global states can be perceived promptly after they started. Application control based on SCGS detection should react quicker to arising situations when using the new algorithm. The quick reactions contribute to a better parallel/distributed application performance. Simulation tests confirm these suppositions. Our solution utilizes bounded maximal message transfer time. It is compared with another method, which employs frequent confirmation messages. While both methods can lead to similar application performance, our approach induces a few times lower both monitor load and network traffic.