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https://issues.apache.org/jira/browse/STORM-1674?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15269608#comment-15269608
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ASF GitHub Bot commented on STORM-1674:
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Github user moesol commented on the pull request:
https://github.com/apache/storm/pull/1391#issuecomment-216666896
Without the MaxWait being set to 100, it is set to 10000, which means that
the bolt will waiting for 10 seconds when no messages are available. On the 1.x
branch, I was going to use:
+ public int fetchMaxWait = FetchRequest.DefaultMaxWait();
+ public int fetchMinBytes = FetchRequest.DefaultMinBytes();
to get Kafka default behavior of 100/1.
> Idle KafkaSpout consumes more bandwidth than needed
> ---------------------------------------------------
>
> Key: STORM-1674
> URL: https://issues.apache.org/jira/browse/STORM-1674
> Project: Apache Storm
> Issue Type: Bug
> Components: storm-kafka
> Affects Versions: 0.9.3
> Reporter: Robert Hastings
>
> Discovered 30 megabits of traffic flowing between a set of KafkaSpouts
> and our kafka servers even though no Kafka messages were moving.
> Using the wireshark kafka dissector, we were able to see that
> each FetchRequest had maxWait set to 10000
> and minBytes set to 0. When binBytes is set to 0 the kafka server
> responds immediately when there are no messages. In turn the KafkaSpout
> polls without any delay causing a constant stream of FetchRequest/
> FetchResponse messages. Using a non-KafkaSpout client had a similar
> traffic pattern with two key differences
> 1) minBytes was 1
> 2) maxWait was 100
> With these FetchRequest parameters and no messages flowing,
> the kafka server delays the FetchResponse by 100 ms. This reduces
> the network traffic from megabits to the low kilobits. It also
> reduced the CPU utilization of our kafka server from 140% to 2%.
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