James Cheng created KAFKA-7144: ---------------------------------- Summary: Kafka Streams doesn't properly balance partition assignment Key: KAFKA-7144 URL: https://issues.apache.org/jira/browse/KAFKA-7144 Project: Kafka Issue Type: Bug Components: streams Affects Versions: 1.1.0 Reporter: James Cheng Attachments: OneThenTwelve.java
Kafka Streams doesn't always spread the tasks across all available instances/threads I have a topology which consumes a single partition topic and goes .through() a 12 partition topic. The makes 13 partitions. I then started 2 instances of the application. I would have expected the 13 partitions to be split across the 2 instances roughly evenly (7 partitions on one, 6 partitions on the other). Instead, one instance gets 12 partitions, and the other instance gets 1 partition. Repro case attached. I ran it a couple times, and it was fairly repeatable. Setup for the repro: {code:java} $ ./bin/kafka-topics.sh --zookeeper localhost --create --topic one --partitions 1 --replication-factor 1 $ ./bin/kafka-topics.sh --zookeeper localhost --create --topic twelve --partitions 12 --replication-factor 1 $ echo foo | kafkacat -P -b 127.0.0.1 -t one {code} -- This message was sent by Atlassian JIRA (v7.6.3#76005)