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Posted to jira@kafka.apache.org by "Kalpesh Patel (Jira)" <ji...@apache.org> on 2021/04/21 16:43:00 UTC
[jira] [Assigned] (KAFKA-12704) Concurrent calls to
AbstractHerder::getConnector can potentially create two connector instances
[ https://issues.apache.org/jira/browse/KAFKA-12704?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Kalpesh Patel reassigned KAFKA-12704:
-------------------------------------
Assignee: Kalpesh Patel
> Concurrent calls to AbstractHerder::getConnector can potentially create two connector instances
> -----------------------------------------------------------------------------------------------
>
> Key: KAFKA-12704
> URL: https://issues.apache.org/jira/browse/KAFKA-12704
> Project: Kafka
> Issue Type: Bug
> Components: KafkaConnect
> Reporter: Kalpesh Patel
> Assignee: Kalpesh Patel
> Priority: Minor
>
> Requests to the {{PUT /connector-plugins/\{connectorType}/config/validate}} endpoint are [delegated to the herder|https://github.com/apache/kafka/blob/16ee326755e3f13914a0ed446c34c84e65fc0bc4/connect/runtime/src/main/java/org/apache/kafka/connect/runtime/rest/resources/ConnectorPluginsResource.java#L81], which [caches connector instances|https://github.com/apache/kafka/blob/16ee326755e3f13914a0ed446c34c84e65fc0bc4/connect/runtime/src/main/java/org/apache/kafka/connect/runtime/AbstractHerder.java#L536-L544] that are used [during config validation|https://github.com/apache/kafka/blob/16ee326755e3f13914a0ed446c34c84e65fc0bc4/connect/runtime/src/main/java/org/apache/kafka/connect/runtime/AbstractHerder.java#L310]. This has the effect that, should concurrent requests to that endpoint occur for the same connector type, the same connector instance may be responsible for [validating those configurations|https://github.com/apache/kafka/blob/16ee326755e3f13914a0ed446c34c84e65fc0bc4/connect/runtime/src/main/java/org/apache/kafka/connect/runtime/AbstractHerder.java#L334] concurrently _(may_ instead of _will_ because there is also a race condition in the {{AbstractHerder::getConnector}} method that potentially fails to detect that an instance of the connector has already been created and, as a result, creates a second instance).
> This is slightly problematic because the [Connector::validate|https://github.com/apache/kafka/blob/16ee326755e3f13914a0ed446c34c84e65fc0bc4/connect/api/src/main/java/org/apache/kafka/connect/connector/Connector.java#L122-L127] method is not marked as thread-safe. However, because a lot of connectors out there tend to use the default implementation for that method, it's probably not super urgent that we patch this immediately.
> A couple of options are:
> # Update the docs for that method to specify that it must be thread-safe
> # Rewrite the connector validation logic in the framework to avoid concurrently invoking {{Connector::validate}} on the same instance.
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