[
https://issues.apache.org/jira/browse/KAFKA-3727?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15340699#comment-15340699
]
Edoardo Comar commented on KAFKA-3727:
--------------------------------------
[~ijuma] and [~hachikuji] referring to your comments in
https://github.com/apache/kafka/pull/1428 :
{quote}
the user ultimately has to monitor the progress of the application and take
steps when it is failing or falling behind.
{quote}
I think that a general approach to handle calls that hang due to loops that
retry forever,
(for whatever reason : partition/topic not existing, connection refused, wrong
credentials ...)
would be to add to the KafkaConsumer a simple listener, e.g.
{code}
void onException(Exception e);
{code}
listener that gets notified of the internal 'failures' that are treated as
retriable.
This would enable the client code to {{wakeup()}} the consumer and have it exit
the never ending loop.
What do you think ? Does this need a KIP ?
> Consumer.poll() stuck in loop on non-existent topic manually assigned
> ---------------------------------------------------------------------
>
> Key: KAFKA-3727
> URL: https://issues.apache.org/jira/browse/KAFKA-3727
> Project: Kafka
> Issue Type: Bug
> Components: clients
> Reporter: Edoardo Comar
> Assignee: Edoardo Comar
> Priority: Critical
>
> The behavior of a consumer on poll() for a non-existing topic is surprisingly
> different/inconsistent
> between a consumer that subscribed to the topic and one that had the
> topic-partition manually assigned.
> The "subscribed" consumer will return an empty collection
> The "assigned" consumer will *loop forever* - this feels a bug to me.
> sample snippet to reproduce:
> {quote}
> KafkaConsumer<String, String> assignKc = new KafkaConsumer<>(props1);
> KafkaConsumer<String, String> subsKc = new KafkaConsumer<>(props2);
> List<TopicPartition> tps = new ArrayList<>();
> tps.add(new TopicPartition("topic-not-exists", 0));
> assignKc.assign(tps);
> subsKc.subscribe(Arrays.asList("topic-not-exists"));
> System.out.println("********* subscribe k consumer ");
> ConsumerRecords<String, String> crs2 = subsKc.poll(1000L);
> print("subscribeKc", crs2); // returns empty
> System.out.println("********* assign k consumer ");
> ConsumerRecords<String, String> crs1 = assignKc.poll(1000L);
> // will loop forever !
> print("assignKc", crs1);
> {quote}
> the logs for the "assigned" consumer show:
> [2016-05-18 17:33:09,907] DEBUG Updated cluster metadata version 8 to
> Cluster(nodes = [192.168.10.18:9093 (id: 0 rack: null)], partitions = [])
> (org.apache.kafka.clients.Metadata)
> [2016-05-18 17:33:09,908] DEBUG Partition topic-not-exists-0 is unknown for
> fetching offset, wait for metadata refresh
> (org.apache.kafka.clients.consumer.internals.Fetcher)
> [2016-05-18 17:33:10,010] DEBUG Sending metadata request
> {topics=[topic-not-exists]} to node 0 (org.apache.kafka.clients.NetworkClient)
> [2016-05-18 17:33:10,011] WARN Error while fetching metadata with correlation
> id 9 : {topic-not-exists=UNKNOWN_TOPIC_OR_PARTITION}
> (org.apache.kafka.clients.NetworkClient)
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
