使用内存后端时Flink Checkpoint为何大幅提升延迟？

架构老林

2026-5-12

最近我在基于Flink做测试时碰到了一个费解的问题：当使用内存状态后端并开启Checkpoint后，作业的延迟出现了远超预期的飙升，哪怕Checkpoint本身的耗时看起来非常短。

核心现象

开启Checkpoint后，尽管Checkpoint端到端耗时仅50ms，但在15:35:46,385注入的事件直到15:35:46,905才到达下游，延迟高达520ms，这段时间内完全没有事件处理。
未开启Checkpoint时，作业的99.99%分位延迟仅约15ms，性能表现正常。

Checkpoint日志详情

2019-02-27 15:35:46,322 INFO org.apache.flink.runtime.checkpoint.CheckpointCoordinator - Triggering checkpoint 2 @ 1551281746322 for job a80597b3312f0704beed75397c371bf5.
2019-02-27 15:35:46,326 INFO org.apache.flink.runtime.state.heap.HeapKeyedStateBackend - Heap backend snapshot (In-Memory Stream Factory, synchronous part) in thread Thread[KeyedProcess -> Map -> Sink: Unnamed (1/1),5,Flink Task Threads] took 0 ms.
2019-02-27 15:35:46,342 INFO org.apache.flink.runtime.state.DefaultOperatorStateBackend - DefaultOperatorStateBackend snapshot (In-Memory Stream Factory, synchronous part) in thread Thread[Async calls on Source: Custom Source -> Map -> Timestamps/Watermarks (1/1),5,Flink Task Threads] took 2 ms.
2019-02-27 15:35:46,346 INFO org.apache.flink.runtime.state.DefaultOperatorStateBackend - DefaultOperatorStateBackend snapshot (In-Memory Stream Factory, asynchronous part) in thread Thread[pool-14-thread-2,5,Flink Task Threads] took 3 ms.
2019-02-27 15:35:46,351 INFO org.apache.flink.runtime.state.heap.HeapKeyedStateBackend - Heap backend snapshot (In-Memory Stream Factory, asynchronous part) in thread Thread[pool-11-thread-2,5,Flink Task Threads] took 14 ms.
2019-02-27 15:35:46,378 INFO org.apache.flink.runtime.checkpoint.CheckpointCoordinator - Completed checkpoint 2 for job a80597b3312f0704beed75397c371bf5 (1157653 bytes in 54 ms).