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https://issues.apache.org/jira/browse/FLINK-10674?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16681497#comment-16681497
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ASF GitHub Bot commented on FLINK-10674:
----------------------------------------
wenhuitang opened a new pull request #7076: [Patch]:Fix
[FLINK-10674]DistinctAccumulator.remove lead to NPE.
URL: https://github.com/apache/flink/pull/7076
## What is the purpose of the change
This pull request fixes the problem reported by FLINK-10674
DistinctAccumulator.remove lead to NPE.
## Brief change log
DistinctAccumulator.remove deals with the situation that there is no
corresponding instance of the parameters in the distinct map.
## Verifying this change
*(Please pick either of the following options)*
This change is a trivial rework / code cleanup without any test coverage.
## Does this pull request potentially affect one of the following parts:
- Dependencies (does it add or upgrade a dependency): (yes / no) no
- The public API, i.e., is any changed class annotated with
`@Public(Evolving)`: (yes / no) no
- The serializers: (yes / no / don't know) no
- The runtime per-record code paths (performance sensitive): (yes / no /
don't know) no
- Anything that affects deployment or recovery: JobManager (and its
components), Checkpointing, Yarn/Mesos, ZooKeeper: (yes / no / don't know) no
- The S3 file system connector: (yes / no / don't know) no
## Documentation
- Does this pull request introduce a new feature? (yes / no)
no
- If yes, how is the feature documented? (not applicable / docs / JavaDocs
/ not documented)
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> DistinctAccumulator.remove lead to NPE
> --------------------------------------
>
> Key: FLINK-10674
> URL: https://issues.apache.org/jira/browse/FLINK-10674
> Project: Flink
> Issue Type: Bug
> Components: Table API & SQL
> Affects Versions: 1.6.1
> Environment: Flink 1.6.0
> Reporter: ambition
> Assignee: winifredtang
> Priority: Minor
> Labels: pull-request-available
> Attachments: image-2018-10-25-14-46-03-373.png
>
>
> Our online Flink Job run about a week，job contain sql ：
> {code:java}
> select `time`,
> lower(trim(os_type)) as os_type,
> count(distinct feed_id) as feed_total_view
> from my_table
> group by `time`, lower(trim(os_type)){code}
>
> then occur NPE:
>
> {code:java}
> java.lang.NullPointerException
> at scala.Predef$.Long2long(Predef.scala:363)
> at
> org.apache.flink.table.functions.aggfunctions.DistinctAccumulator.remove(DistinctAccumulator.scala:109)
> at NonWindowedAggregationHelper$894.retract(Unknown Source)
> at
> org.apache.flink.table.runtime.aggregate.GroupAggProcessFunction.processElement(GroupAggProcessFunction.scala:124)
> at
> org.apache.flink.table.runtime.aggregate.GroupAggProcessFunction.processElement(GroupAggProcessFunction.scala:39)
> at
> org.apache.flink.streaming.api.operators.LegacyKeyedProcessOperator.processElement(LegacyKeyedProcessOperator.java:88)
> at
> org.apache.flink.streaming.runtime.io.StreamInputProcessor.processInput(StreamInputProcessor.java:202)
> at
> org.apache.flink.streaming.runtime.tasks.OneInputStreamTask.run(OneInputStreamTask.java:105)
> at
> org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask.java:300)
> at org.apache.flink.runtime.taskmanager.Task.run(Task.java:711)
> at java.lang.Thread.run(Thread.java:745)
> {code}
>
>
> View DistinctAccumulator.remove
> !image-2018-10-25-14-46-03-373.png!
>
> this NPE should currentCnt = null lead to, so we simple handle like :
> {code:java}
> def remove(params: Row): Boolean = {
> if(!distinctValueMap.contains(params)){
> true
> }else{
> val currentCnt = distinctValueMap.get(params)
> //
> if (currentCnt == null || currentCnt == 1) {
> distinctValueMap.remove(params)
> true
> } else {
> var value = currentCnt - 1L
> if(value < 0){
> value = 1
> }
> distinctValueMap.put(params, value)
> false
> }
> }
> }{code}
>
>
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