Re: flink-1.10 checkpoint 偶尔报 NullPointerException

Mon, 20 Apr 2020 10:24:25 -0700 

Hi

这个NPE有点奇怪，从executeCheckpointing方法[1]里面其实比较难定位究竟是哪一个变量或者变量的取值是null。
一种排查思路是打开 org.apache.flink.streaming.runtime.tasks 的DEBUG 
level日志，通过debug日志缩小范围，判断哪个变量是null

这个异常出现的时候，相关task上面的日志有什么异常么，触发这个NPE的条件是什么，稳定复现么？

[1] 
https://github.com/apache/flink/blob/aa4eb8f0c9ce74e6b92c3d9be5dc8e8cb536239d/flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/tasks/StreamTask.java#L1349

祝好
唐云

________________________________
From: chenkaibit <chenkai...@163.com>
Sent: Monday, April 20, 2020 18:39
To: user-zh@flink.apache.org <user-zh@flink.apache.org>
Subject: flink-1.10 checkpoint 偶尔报 NullPointerException

大家遇到过这个错误吗, CheckpointOperation.executeCheckpointing 的时候报 NullPointerException
java.lang.Exception: Couldnot perform checkpoint 5505for operator Source: 
KafkaTableSource(xxx) -> SourceConversion(table=[xxx, source: 
[KafkaTableSource(xxx)]], fields=[xxx]) -> Calc(select=[xxx) AS xxx]) -> 
SinkConversionToTuple2 -> Sink: Elasticsearch6UpsertTableSink(xxx) (1/1).

    at 
org.apache.flink.streaming.runtime.tasks.StreamTask.triggerCheckpoint(StreamTask.java:802)

    at 
org.apache.flink.streaming.runtime.tasks.StreamTask.lambda$triggerCheckpointAsync$3(StreamTask.java:777)

    at 
org.apache.flink.streaming.runtime.tasks.StreamTask$$Lambda$228/1024478318.call(UnknownSource)

    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:487)

    at 
org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask.java:470)

    at org.apache.flink.runtime.taskmanager.Task.doRun(Task.java:707)

    at org.apache.flink.runtime.taskmanager.Task.run(Task.java:532)

    at java.lang.Thread.run(Thread.java:745)

Causedby: java.lang.NullPointerException

    at 
org.apache.flink.streaming.runtime.tasks.StreamTask$CheckpointingOperation.executeCheckpointing(StreamTask.java:1411)

    at 
org.apache.flink.streaming.runtime.tasks.StreamTask.checkpointState(StreamTask.java:991)

    at 
org.apache.flink.streaming.runtime.tasks.StreamTask.lambda$performCheckpoint$5(StreamTask.java:887)

    at 
org.apache.flink.streaming.runtime.tasks.StreamTask$$Lambda$229/1010499540.run(UnknownSource)

    at 
org.apache.flink.streaming.runtime.tasks.StreamTaskActionExecutor$SynchronizedStreamTaskActionExecutor.runThrowing(StreamTaskActionExecutor.java:94)

    at 
org.apache.flink.streaming.runtime.tasks.StreamTask.performCheckpoint(StreamTask.java:860)

    at 
org.apache.flink.streaming.runtime.tasks.StreamTask.triggerCheckpoint(StreamTask.java:793)

    ... 12 more

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