[ https://issues.apache.org/jira/browse/KAFKA-12564?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Matthias J. Sax resolved KAFKA-12564. ------------------------------------- Resolution: Not A Bug > KTable#filter-method called twice after aggregation > --------------------------------------------------- > > Key: KAFKA-12564 > URL: https://issues.apache.org/jira/browse/KAFKA-12564 > Project: Kafka > Issue Type: Bug > Components: streams > Affects Versions: 2.7.0 > Reporter: Jessica Johann > Priority: Major > > Libraries from build.sbt: > {{"org.apache.kafka" % "kafka_2.13" % "2.7.0",}} > {{"org.apache.kafka" % "kafka-streams" % "2.7.0",}} > {{"org.apache.kafka" % "kafka-clients" % "2.7.0",}} > {{"org.apache.kafka" % "kafka-streams-scala_2.13" % "2.7.0",}} > h4. > h4. Feed the Stream "issue_stream" with: > {{(1->"A")}} > {{(1->"B")}} > h4. > h4. Topology: > {{// #1}} > {{val issueStream:KStream[Int,String] = > builder.stream[Int,String]("issue_stream")}} > > {{// #2}} > {{val aggTable:KTable[Int,String] =}} > {{issueStream}} > {{.groupBy((k,v)=>k)}} > {{.aggregate[String]("EMPTY")((k,v,agg)=>s"$agg+$v")}} > > {{// #3}} > {{aggTable}} > {{.toStream}} > {{.print(Printed.toSysOut)}} > > {{// #4}} > {{aggTable.filter((k,v)=> {}} > {{ println(s"filter($k, $v) at ${System.nanoTime()}")}} > {{ true}} > {{})}} > {{.toStream}} > {{.print(Printed.toSysOut)}} > h4. > h4. First Tuple: (1->"A") > #3 Output as expected, the aggregated tuple ("EMPTY"+"+A") > {{[KTABLE-TOSTREAM-0000000044]: 1, EMPTY+A}} > > #4 The filter-method is called twice. > First call with the expected tuple. > {{filter(1, EMPTY+A) at 211379567071847}} > The second call with the empty initialized aggregate. > {{filter(1, EMPTY) at 211379567120375}} > Output contains the correct tuple > {{[KTABLE-TOSTREAM-0000000047]: 1, EMPTY+A}} > h4. > h4. Second Tuple: (1->"B") > #3 Output as expected the aggregated tuple ("EMPTY"+"+A"+"+B") > {{[KTABLE-TOSTREAM-0000000044]: 1, EMPTY+A+B}} > #4 Again a second unexpected call to filter(...) with the previous tuple > before aggregation > First call: > {{filter(1, EMPTY+A+B) at 211379567498482}} > Second call: > {{filter(1, EMPTY+A) at 211379567524475}} > But the output contains only one tuple as expected > {{[KTABLE-TOSTREAM-0000000047]: 1, EMPTY+A+B}} -- This message was sent by Atlassian Jira (v8.3.4#803005)