ambition created FLINK-10674:
--------------------------------
Summary: DistinctAccumulator.remove lead to NPE
Key: FLINK-10674
URL: https://issues.apache.org/jira/browse/FLINK-10674
Project: Flink
Issue Type: Bug
Components: flink-contrib
Affects Versions: 1.6.1
Environment: Flink 1.6.0
Reporter: ambition
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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