Emre Kartoglu created FLINK-39003:
-------------------------------------
Summary: Inaccurate millisBehindLatest metric from the Kinesis
source connector on failover
Key: FLINK-39003
URL: https://issues.apache.org/jira/browse/FLINK-39003
Project: Flink
Issue Type: Bug
Components: Connectors / DynamoDB
Affects Versions: aws-connector-5.0.0
Reporter: Emre Kartoglu
Assignee: Emre Kartoglu
We have a Flink app that's reading from DynamoDB streams (not the Kinesis
inteegration). The app is seeing intermittent (pretty rare, so not marking this
ticket as critical) NPEs:
```
java.lang.RuntimeException: SplitFetcher thread 0 received unexpected exception
while polling the records
at
org.apache.flink.connector.base.source.reader.fetcher.SplitFetcher.runOnce(SplitFetcher.java:168)
at
org.apache.flink.connector.base.source.reader.fetcher.SplitFetcher.run(SplitFetcher.java:117)
at
java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
at
java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
at
java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
at java.base/java.lang.Thread.run(Thread.java:829)
Caused by: java.lang.NullPointerException
at
org.apache.flink.connector.dynamodb.source.reader.PollingDynamoDbStreamsShardSplitReader.fetch(PollingDynamoDbStreamsShardSplitReader.java:104)
at
org.apache.flink.connector.base.source.reader.fetcher.FetchTask.run(FetchTask.java:58)
at
org.apache.flink.connector.base.source.reader.fetcher.SplitFetcher.runOnce(SplitFetcher.java:165)
... 6 more
```
Version of the DDB connector:
```
<dependency>
<groupId>org.apache.flink</groupId>
<artifactId>flink-connector-dynamodb</artifactId>
<version>5.0.0-1.20</version>
</dependency>
```
The offending code appears to be
[here|https://github.com/apache/flink-connector-aws/blob/b4047bccf8903ece0553945c19f1d52b313ae84a/flink-connector-aws/flink-connector-dynamodb/src/main/java/org/apache/flink/connector/dynamodb/source/reader/PollingDynamoDbStreamsShardSplitReader.java#L104C1-L111C33]:
```
shardMetrics.setMillisBehindLatest(
Math.max(
System.currentTimeMillis()
- lastRecord
.dynamodb()
.approximateCreationDateTime()
.toEpochMilli(),
0));
```
But it's not clear to me which object in particular is null.
We insert/update/delete from DynamoDB. FWIIW, we also use the TTL functionality
but I'd think that that should be no different than normal the "delete" case in
DDB CDC.
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