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https://issues.apache.org/jira/browse/KAFKA-17044?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17869687#comment-17869687
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Bhagyashree commented on KAFKA-17044:
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Hey [~ChrisEgerton] , sorry for the delay. This connector does retries to get
db connection synchronously. If the time taken by the retries is large, the
start does not fail until the retries are exhausted.
I was looking for a way from the runtime but I got the complexity involved with
it and that a connector developer could prevent this behaviour of start not
finishing for a long time by performing heavy operations async.
Sure, we can close this. Thanks for taking a look.
> Connector deletion can lead to resource leak during a long running connector
> startup
> ------------------------------------------------------------------------------------
>
> Key: KAFKA-17044
> URL: https://issues.apache.org/jira/browse/KAFKA-17044
> Project: Kafka
> Issue Type: Bug
> Components: connect
> Reporter: Bhagyashree
> Priority: Major
>
> We have identified a gap in the shutdown flow for the connector worker. If
> the connector is in
> [INIT|https://github.com/apache/kafka/blob/trunk/connect/runtime/src/main/java/org/apache/kafka/connect/runtime/WorkerConnector.java#L403-L404]
> state and still executing the
> [WorkerConnector::doStart|https://github.com/apache/kafka/blob/trunk/connect/runtime/src/main/java/org/apache/kafka/connect/runtime/WorkerConnector.java#L207-L218]
> method, a DELETE API call would invoke the
> [WorkerConnector::shutdown|https://github.com/apache/kafka/blob/trunk/connect/runtime/src/main/java/org/apache/kafka/connect/runtime/WorkerConnector.java#L294-L298]
> and [notify()
> |https://github.com/apache/kafka/blob/trunk/connect/runtime/src/main/java/org/apache/kafka/connect/runtime/WorkerConnector.java#L297]but
> the connector worker would not shutdown immediately. This happens because
> [start()|https://github.com/apache/kafka/blob/trunk/connect/runtime/src/main/java/org/apache/kafka/connect/runtime/WorkerConnector.java#L216]
> is a blocking call and the control reaches
> [wait()|https://github.com/apache/kafka/blob/trunk/connect/runtime/src/main/java/org/apache/kafka/connect/runtime/WorkerConnector.java#L176]
> in
> [doRun()|https://github.com/apache/kafka/blob/trunk/connect/runtime/src/main/java/org/apache/kafka/connect/runtime/WorkerConnector.java#L151]
> after the
> [start()|https://github.com/apache/kafka/blob/trunk/connect/runtime/src/main/java/org/apache/kafka/connect/runtime/WorkerConnector.java#L216]
> call has completed. This results in a gap in the delete flow where the
> connector is not immediately shutdown leaving the resources running.
> [start()|https://github.com/apache/kafka/blob/trunk/connect/runtime/src/main/java/org/apache/kafka/connect/runtime/WorkerConnector.java#L216]
> keeps running and only when the execution of
> [start()|https://github.com/apache/kafka/blob/trunk/connect/runtime/src/main/java/org/apache/kafka/connect/runtime/WorkerConnector.java#L216]
> completes, we reach at the point of
> [wait()|https://github.com/apache/kafka/blob/trunk/connect/runtime/src/main/java/org/apache/kafka/connect/runtime/WorkerConnector.java#L176]
> and then
> [doShutdown()|https://github.com/apache/kafka/blob/trunk/connect/runtime/src/main/java/org/apache/kafka/connect/runtime/WorkerConnector.java#L183]
> of the connector worker is invoked.
> This seems similar to what has been identified for connector tasks as part of
> https://issues.apache.org/jira/browse/KAFKA-14725.
> *Steps to repro*
> 1. Start a connector with time taking operation in
> [connector.start()|https://github.com/apache/kafka/blob/trunk/connect/runtime/src/main/java/org/apache/kafka/connect/runtime/WorkerConnector.java#L216]
> call
> 2. Call DELETE API to delete this connector
> 3. The connector would be deleted only after the
> [start()|https://github.com/apache/kafka/blob/trunk/connect/runtime/src/main/java/org/apache/kafka/connect/runtime/WorkerConnector.java#L216]
> completes.
> The issue was observed when a connector was configured to retry a db
> connection for sometime.
> {*}Current Behaviour{*}: The connector did not shutdown until the
> [start()|https://github.com/apache/kafka/blob/trunk/connect/runtime/src/main/java/org/apache/kafka/connect/runtime/WorkerConnector.java#L216]
> method completed.
> {*}Expected Behaviou{*}r: The connector should abort what it is doing and
> shutdown as requested by the Delete call.
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