[jira] [Created] (KAFKA-4475) Poor kafka-streams throughput

["Juan Chorro (JIRA)" <ji...@apache.org>]

Juan Chorro created KAFKA-4475:
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             Summary: Poor kafka-streams throughput
                 Key: KAFKA-4475
                 URL: https://issues.apache.org/jira/browse/KAFKA-4475
             Project: Kafka
          Issue Type: Bug
          Components: streams
    Affects Versions: 0.10.1.0
            Reporter: Juan Chorro


Hi! 

I'm writing because I have a worry about kafka-streams throughput.

I have only a kafka-streams application instance that consumes from 'input' topic, prints on the screen and produces in 'output' topic. All topics have 4 partitions. As can be observed the topology is very simple.

I produce 120K messages/second to 'input' topic, when I measure the 'output' topic I detect that I'm receiving ~4K messages/second. I had next configuration (Remaining parameters by default):

application.id: myApp
bootstrap.servers: localhost:9092
zookeeper.connect: localhost:2181
num.stream.threads: 1

I was doing proofs and tests without success, but when I created a new 'input' topic with 1 partition (Maintain 'output' topic with 4 partitions) I got in 'output' topic 120K messages/seconds.

I have been doing some performance tests and proof with next cases (All topics have 4 partitions in all cases):

Case A - 1 Instance:

- With num.stream.threads set to 1 I had ~3785 messages/second
- With num.stream.threads set to 2 I had ~3938 messages/second
- With num.stream.threads set to 4 I had ~120K messages/second

Case B - 2 Instances:

- With num.stream.threads set to 1 I had ~3930 messages/second for each instance (And throughput ~8K messages/second)
- With num.stream.threads set to 2 I had ~3945 messages/second for each instance (And more or less same throughput that with num.stream.threads set to 1)

Case C - 4 Instances

- With num.stream.threads set to 1 I had 3946 messages/seconds for each instance (And throughput ~17K messages/second):

As can be observed when num.stream.threads is set to #partitions I have best results. Then I have next questions:

- Why whether I have a topic with #partitions > 1 and with num.streams.threads is set to 1 I have ~4K messages/second always?
- In case C. 4 instances with num.stream.threads set to 1 should be better that 1 instance with num.stream.threads set to 4. Is corrects this supposition?

This is the kafka-streams application that I use: https://gist.github.com/Chorro/5522ec4acd1a005eb8c9663da86f5a18



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