Flink源码阅读之Checkpoint周期触发过程

Flink的checkpoint原理就不说了，官网以及博客都有说明，有兴趣的同学可以自行查阅。
本文主要从源码层面分析一下checkpoint是如何周期性触发的。

分析

首先通过如下配置启用CheckPoint

env.enableCheckpointing(1000);

不设置，则默认CheckPoint间隔为-1，即不启用CheckPoint

/** Periodic checkpoint triggering interval. */
private long checkpointInterval = -1; // disabled

如不设置则在构建jobGraph时checkpointInterval 会被赋值为Long.MAX_VALUE
StreamingJobGraphGenerator#configureCheckpointing

long interval = cfg.getCheckpointInterval();
if (interval < MINIMAL_CHECKPOINT_TIME) {
   
	// interval of max value means disable periodic checkpoint
	interval = Long.MAX_VALUE;
}

同时会初始化三个列表：

// collect the vertices that receive "trigger checkpoint" messages.
		// currently, these are all the sources
		List<JobVertexID> triggerVertices = new ArrayList<>();

		// collect the vertices that need to acknowledge the checkpoint
		// currently, these are all vertices
		List<JobVertexID> ackVertices = new ArrayList<>(jobVertices.size());

		// collect the vertices that receive "comm