Latency-Oriented Elastic Memory Management at Task-Granularity for Stateful Streaming Processing.

In a streaming application, an operator is usually instantiated into multiple tasks for parallel processing. Tasks across operators have various memory demands due to different processing logic (e.g., stateful vs. stateless tasks). The memory demands of tasks from the same operator could also vary and fluctuate due to workload variability. Improper memory provision will cause some tasks to have relatively high latency, or even unbound latency that can eventually lead to system instability. We found that the task with the maximum latency of an operator has a significant and even decisive impact on the end-to-end latency.In this paper, we present our task-level memory manager. Based on our quantitative modeling of memory and task-level latency, the manager can adaptively allocate optimal memory size to each task for minimizing the end-to-end latency. We integrate our memory management on Apache Flink. The experiments show that our memory management could significantly reduce end-to-end latency for various applications at different scales and configurations, compared to the Flink native setting.