最近实时平台flink任务频繁失败，报检查点方面的错误，最近集群的hdfs也经常报警：运行状况不良，不知道是否和该情况有关，我的状态后端位置是hdfs，废话不多说，干货搞起来~
问题描述
日志中报错如下：
2022-07-16 06:26:46,566 INFO org.apache.flink.runtime.checkpoint.CheckpointCoordinator [] - Checkpoint 670223 of job 61103d713243c4a71befb436fa3f32ee expired before completing. 2022-07-16 06:26:46,571 INFO org.apache.flink.runtime.jobmaster.JobMaster [] - Trying to recover from a global failure. org.apache.flink.util.FlinkRuntimeException: Exceeded checkpoint tolerable failure threshold. at org.apache.flink.runtime.checkpoint.CheckpointFailureManager.handleCheckpointException(CheckpointFailureManager.java:98) ~[flink-dist_2.11-1.13.1.jar:1.13.1] at org.apache.flink.runtime.checkpoint.CheckpointFailureManager.handleJobLevelCheckpointException(CheckpointFailureManager.java:67) ~[flink-dist_2.11-1.13.1.jar:1.13.1] at org.apache.flink.runtime.checkpoint.CheckpointCoordinator.abortPendingCheckpoint(CheckpointCoordinator.java:1934) ~[flink-dist_2.11-1.13.1.jar:1.13.1] at org.apache.flink.runtime.checkpoint.CheckpointCoordinator.abortPendingCheckpoint(CheckpointCoordinator.java:1906) ~[flink-dist_2.11-1.13.1.jar:1.13.1] at org.apache.flink.runtime.checkpoint.CheckpointCoordinator.access$600(CheckpointCoordinator.java:96) ~[flink-dist_2.11-1.13.1.jar:1.13.1] at org.apache.flink.runtime.checkpoint.CheckpointCoordinator$CheckpointCanceller.run(CheckpointCoordinator.java:1990) ~[flink-dist_2.11-1.13.1.jar:1.13.1] at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) ~[?:1.8.0_201] at java.util.concurrent.FutureTask.run(FutureTask.java:266) ~[?:1.8.0_201] at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180) ~[?:1.8.0_201] at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293) ~[?:1.8.0_201] at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) ~[?:1.8.0_201] at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) ~[?:1.8.0_201] at java.lang.Thread.run(Thread.java:748) ~[?:1.8.0_201]
注意：
在报Exceeded checkpoint tolerable failure threshold.错误的之前，是先报的是Checkpoint expired before completing.大概意思是检查点在完成前过期了。
解决方案：
这个错误也是头一次见，更让我好奇的是报这个错误的时间点大概差不多(每两天大概报一次，早晨6点多)。
最开始调整了检查点的频率(5s -> 10s)和任务重启间隔(5s -> 30s)，以为频率太快了,但调整后并没能解决该问题。
后来又将jobmanager和taskmanager运行内存调大，但也没能解决…
通过查找flink检查点相关配置，发现了配置项TolerableCheckpointFailureNumber即可容忍检查点失败次数的配置，默认值为0表示不允许容忍任何检查点失败。
报的错就是超过检查点可容忍失败阈值，试试观察观察再说，因此在程序里加上了这个配置。
//设置可容忍的检查点失败数，默认值为0表示不允许容忍任何检查点失败 env.getCheckpointConfig().setTolerableCheckpointFailureNumber(2);
配置说明：
限制的是最大可容忍的连续失败checkpoint计数 continuousFailureCounter，例如将tolerableCheckpointFailureNumber设置成3，连续失败3次，continuousFailureCounter会累计到3，作业就会尝试重启。如果中间有一个checkpoint成功了，continuousFailureCounter 就会重置为零。
按之前的规律第二天任务就得报这个错误失败了，查看flink任务web界面，任务正常，但检查点确实失败过一次，也是大概那个时间失败的，失败原因和之前一样Checkpoint expired before completing.
说明该配置对报错的解决有效，问题解决！！！
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