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https://issues.apache.org/jira/browse/FLINK-10674?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16695894#comment-16695894
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ASF GitHub Bot commented on FLINK-10674:
----------------------------------------
fhueske commented on a change in pull request #7147: [FLINK-10674] [table] Fix
handling of retractions after clean up
URL: https://github.com/apache/flink/pull/7147#discussion_r235723629
##########
File path:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/runtime/aggregate/GroupAggProcessFunction.scala
##########
@@ -95,6 +95,12 @@ class GroupAggProcessFunction(
var inputCnt = cntState.value()
if (null == accumulators) {
+ // don't create a new accumulator for unknown retractions
Review comment:
The retraction is not unknown, IMO.
I'd rephrase comment: "Don't create a new accumulator for a retraction
message. This might happen if the retraction message is the first message for
the key or after a state clean up."
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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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