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https://issues.apache.org/jira/browse/KAFKA-16838?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17851304#comment-17851304
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Sergey Ivanov commented on KAFKA-16838:
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Hi [~ChrisEgerton], thanks for the answer, but still for my understanding, on
connector remove we also send tombstone messages for connector "config" and
"target" records, why can't we just do the same for "task" and "commit" records?
> Kafka Connect loads old tasks from removed connectors
> -----------------------------------------------------
>
> Key: KAFKA-16838
> URL: https://issues.apache.org/jira/browse/KAFKA-16838
> Project: Kafka
> Issue Type: Bug
> Components: connect
> Affects Versions: 3.5.1, 3.6.1, 3.8.0
> Reporter: Sergey Ivanov
> Assignee: Chris Egerton
> Priority: Major
>
> Hello,
> When creating connector we faced an error from one of our ConfigProviders
> about not existing resource, but we didn't try to set that resource as config
> value:
> {code:java}
> [2024-05-24T12:08:24.362][ERROR][request_id= ][tenant_id=
> ][thread=DistributedHerder-connect-1-1][class=org.apache.kafka.connect.runtime.distributed.DistributedHerder][method=lambda$reconfigureConnectorTasksWithExponentialBackoffRetries$44]
> [Worker clientId=connect-1, groupId=streaming-service_streaming_service]
> Failed to reconfigure connector's tasks (local-file-sink), retrying after
> backoff.
> org.apache.kafka.common.config.ConfigException: Could not read properties
> from file /opt/kafka/provider.properties
> at
> org.apache.kafka.common.config.provider.FileConfigProvider.get(FileConfigProvider.java:98)
> at
> org.apache.kafka.common.config.ConfigTransformer.transform(ConfigTransformer.java:103)
> at
> org.apache.kafka.connect.runtime.WorkerConfigTransformer.transform(WorkerConfigTransformer.java:58)
> at
> org.apache.kafka.connect.storage.ClusterConfigState.taskConfig(ClusterConfigState.java:181)
> at
> org.apache.kafka.connect.runtime.AbstractHerder.taskConfigsChanged(AbstractHerder.java:804)
> at
> org.apache.kafka.connect.runtime.distributed.DistributedHerder.publishConnectorTaskConfigs(DistributedHerder.java:2089)
> at
> org.apache.kafka.connect.runtime.distributed.DistributedHerder.reconfigureConnector(DistributedHerder.java:2082)
> at
> org.apache.kafka.connect.runtime.distributed.DistributedHerder.reconfigureConnectorTasksWithExponentialBackoffRetries(DistributedHerder.java:2025)
> at
> org.apache.kafka.connect.runtime.distributed.DistributedHerder.lambda$null$42(DistributedHerder.java:2038)
> at
> org.apache.kafka.connect.runtime.distributed.DistributedHerder.runRequest(DistributedHerder.java:2232)
> at
> org.apache.kafka.connect.runtime.distributed.DistributedHerder.tick(DistributedHerder.java:470)
> at
> org.apache.kafka.connect.runtime.distributed.DistributedHerder.run(DistributedHerder.java:371)
> at
> java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:539)
> at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
> at
> java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
> at
> java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
> at java.base/java.lang.Thread.run(Thread.java:840)
> {code}
> It looked like there already was connector with the same name and same
> config, +but it wasn't.+
> After investigation we found out, that few months ago on that cloud there was
> the connector with the same name and another value for config provider. Then
> it was removed, but by some reason when we tried to create connector with the
> same name months ago AbstractHerder tried to update tasks from our previous
> connector
> As an example I used FileConfigProvider, but actually any ConfigProvider is
> acceptable which could raise exception if something wrong with config (like
> result doesn't exist).
> We continued our investigation and found the issue
> https://issues.apache.org/jira/browse/KAFKA-7745 that says Connect doesn't
> send tombstone message for *commit* and *task* records in the config topic of
> Kafka Connect. As we remember, the config topic is `compact` *that means
> commit and tasks are are always stored* (months, years after connector
> removing) while tombstones for connector messages are cleaned with
> {{delete.retention.ms}} property. That impacts further connector creations
> with the same name.
> We didn't investigate reasons in ConfigClusterStore and how to avoid that
> issue, because would {+}like to ask{+}, probably it's better to fix
> KAFKA-7745 and send tombstones for commit and task messages as connect does
> for connector and target messages?
> In the common way the TC looks like:
> # Create connector with config provider to resource1
> # Remove connector
> # Remove resouce1
> # Wait 2-4 weeks :) (until config topic being compacted and tombstone
> messages about config and target connector are removed)
> # Try to create connector with the same name and config provider to resource2
> I can provide synthetic TC to reproduce that error if needed.
>
> This is linked with https://issues.apache.org/jira/browse/KAFKA-16837 but
> it's not the same issue.
> As WA we can remove connector one more time, to get *tombstone* message for
> connector in config topic.
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