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https://issues.apache.org/jira/browse/KAFKA-3854?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15360746#comment-15360746
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ASF GitHub Bot commented on KAFKA-3854:
---------------------------------------
Github user vahidhashemian closed the pull request at:
https://github.com/apache/kafka/pull/1572
> Subsequent regex subscription calls fail
> ----------------------------------------
>
> Key: KAFKA-3854
> URL: https://issues.apache.org/jira/browse/KAFKA-3854
> Project: Kafka
> Issue Type: Bug
> Components: consumer
> Reporter: Vahid Hashemian
> Assignee: Vahid Hashemian
>
> There are a couple of issues with regex subscription in the new consumer:
> h6. Subsequent Subscriptions Fail
> When consecutive calls are made to new consumer's [regex
> subscription|https://github.com/apache/kafka/blob/trunk/clients/src/main/java/org/apache/kafka/clients/consumer/KafkaConsumer.java#L850],
> like below:
> {code}
> consumer.subscribe(Pattern.compile("..."), listener);
> consumer.poll(0);
> consumer.subscribe(Pattern.compile("f.."), listener);
> consumer.poll(0);
> {code}
> the second call fails with the following error:
> {code}
> Exception in thread "main" java.lang.IllegalStateException: Subscription to
> topics, partitions and pattern are mutually exclusive
> at
> org.apache.kafka.clients.consumer.internals.SubscriptionState.subscribe(SubscriptionState.java:175)
> at
> org.apache.kafka.clients.consumer.KafkaConsumer.subscribe(KafkaConsumer.java:854)
> ...
> {code}
> h6. Subsequent Subscriptions Fail to Trigger a Subscription Change and
> Rebalance
> Even after the code is tweaked to get around the above issue, only the first
> call to regex subscription triggers an actual subscription and the
> subscription's rebalance listener. The reason is the regex {{subscription}} /
> {{poll}} does not directly call {{changeSubscription(...)}} in which
> {{needsPartitionAssignment}} is set and causes a rebalance. This method is
> called only during the first regex {{subscription}} / {{poll}} when
> coordinator is unknown and [a {{client.poll}}
> call|https://github.com/apache/kafka/blob/trunk/clients/src/main/java/org/apache/kafka/clients/consumer/internals/AbstractCoordinator.java#L179]
> is made which eventually leads to [a {{changeSubscription}}
> call|https://github.com/apache/kafka/blob/trunk/clients/src/main/java/org/apache/kafka/clients/consumer/internals/ConsumerCoordinator.java#L161].
> The subsequent call does not reach this point because the coordinator is
> already known.
> It seems due to the same reason, if a consumer is subscribed to a pattern,
> and later on a new topic is created that matches that pattern, the consumer
> does not become subscribed it.
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