我运行了flink作业，但18小时后失败了。失败消息：Checkpoint协调器正在挂起。 Checkpoint screenshot ， Job overview screenshot
这是作业管理器日志：
2020-10-10 13:53:10,636 INFO org.apache.flink.runtime.executiongraph.ExecutionGraph - Source: kafkaSource -> Timestamps/Watermarks -> Process (1/1) (c38419ece8208c1ef2948087f2b84dd0) switched from RUNNING to FAILED.
java.lang.Exception: Could not perform checkpoint 3265 for operator Source: kafkaSource -> Timestamps/Watermarks -> Process (1/1).
at org.apache.flink.streaming.runtime.tasks.StreamTask.triggerCheckpoint(StreamTask.java:785)
at org.apache.flink.streaming.runtime.tasks.StreamTask.lambda$triggerCheckpointAsync$3(StreamTask.java:760)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at org.apache.flink.streaming.runtime.tasks.StreamTaskActionExecutor$SynchronizedStreamTaskActionExecutor.run(StreamTaskActionExecutor.java:87)
at org.apache.flink.streaming.runtime.tasks.mailbox.Mail.run(Mail.java:78)
at org.apache.flink.streaming.runtime.tasks.mailbox.MailboxProcessor.processMail(MailboxProcessor.java:261)
at org.apache.flink.streaming.runtime.tasks.mailbox.MailboxProcessor.runMailboxLoop(MailboxProcessor.java:186)
at org.apache.flink.streaming.runtime.tasks.StreamTask.runMailboxLoop(StreamTask.java:485)
at org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask.java:469)
at org.apache.flink.runtime.taskmanager.Task.doRun(Task.java:708)
at org.apache.flink.runtime.taskmanager.Task.run(Task.java:533)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.NullPointerException
at org.apache.flink.streaming.runtime.tasks.StreamTask$CheckpointingOperation.executeCheckpointing(StreamTask.java:1394)
at org.apache.flink.streaming.runtime.tasks.StreamTask.checkpointState(StreamTask.java:974)
at org.apache.flink.streaming.runtime.tasks.StreamTask.lambda$performCheckpoint$5(StreamTask.java:870)
at org.apache.flink.streaming.runtime.tasks.StreamTaskActionExecutor$SynchronizedStreamTaskActionExecutor.runThrowing(StreamTaskActionExecutor.java:94)
at org.apache.flink.streaming.runtime.tasks.StreamTask.performCheckpoint(StreamTask.java:843)
at org.apache.flink.streaming.runtime.tasks.StreamTask.triggerCheckpoint(StreamTask.java:776)
... 11 more
我不知道是什么原因导致了这个问题。