[jira] [Created] (KAFKA-13220) Group or Group Coordinator logs are misleading when using assign(partitions) method in Consumer API.

[nandini (Jira)]

nandini created KAFKA-13220:
-------------------------------

             Summary: Group or Group Coordinator logs are misleading when using 
assign(partitions) method in Consumer API.
                 Key: KAFKA-13220
                 URL: https://issues.apache.org/jira/browse/KAFKA-13220
             Project: Kafka
          Issue Type: Bug
          Components: clients
            Reporter: nandini


Kafka console consumer does not allow us to to use group and partition together 
https://github.com/apache/kafka/blob/trunk/core/src/main/scala/kafka/tools/ConsoleConsumer.scala#L395

Hence, on Manual topic assignment through this method does not use the 
consumer's group management functionality. 
https://kafka.apache.org/26/javadoc/org/apache/kafka/clients/consumer/KafkaConsumer.html#assign-java.util.Collection-

But as when using the API and implementing your own Kafka Consumer, you can 
specify group.id and use consumer.assign(partitions);
While gives an impression that the client is using the group (however it is not 
printed as an active consumer in kafka-consumer-groups describe output for that 
topic)
Even if you do not specify a group.id it prints logs from GroupCoordinator 
This is misleading.

{{Code- }}
{quote}{{Properties props = new Properties();}}
{{ props.setProperty(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, 
bootstrapServers);}}
{{ props.setProperty(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, 
StringDeserializer.class.getName());}}
{{ props.setProperty(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, 
ByteArrayDeserializer.class.getName());}}
{{ props.setProperty(ConsumerConfig.GROUP_ID_CONFIG, 
mygroup);}}{{List<TopicPartition> partitions = new 
ArrayList<TopicPartition>();}}
{{ partitions.add(new TopicPartition("mytopic", 0));}}
{{ consumer.assign(partitions);}}
{quote}
{{Logs -}}

{{-- when group.id is specified}}
{quote}[main] INFO org.apache.kafka.clients.consumer.internals.Fetcher - 
[Consumer clientId=consumer-1, groupId=mygroup] Resetting offset for partition 
mytopic-0 to offset 0.
[main] INFO com.cloudera.kafka.SimpleConsumer - Key: null, Value: [B@7bc1a03d
[main] INFO com.cloudera.kafka.SimpleConsumer - Partition: 0, Offset:0
{quote}
-- when group.id is not specified
{quote}[main] INFO 
org.apache.kafka.clients.consumer.internals.AbstractCoordinator - [Consumer 
clientId=consumer-1, groupId=] Discovered group coordinator hostname:9092 (id: 
2147483647 rack: null)
[main] INFO org.apache.kafka.clients.consumer.internals.Fetcher - [Consumer 
clientId=consumer-1, groupId=] Resetting offset for partition mytopic-0 to 
offset 0.
{quote}



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