[jira] [Resolved] (KAFKA-1417) Very slow initial high-level consumer startup in low traffic/blocking fetch scenario

["Sam Meder (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/KAFKA-1417?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Sam Meder resolved KAFKA-1417.
------------------------------

       Resolution: Fixed
    Fix Version/s: 0.8.1

> Very slow initial high-level consumer startup in low traffic/blocking fetch scenario
> ------------------------------------------------------------------------------------
>
>                 Key: KAFKA-1417
>                 URL: https://issues.apache.org/jira/browse/KAFKA-1417
>             Project: Kafka
>          Issue Type: Bug
>          Components: consumer
>    Affects Versions: 0.8.0
>            Reporter: Sam Meder
>            Assignee: Neha Narkhede
>             Fix For: 0.8.1
>
>
> We're seeing very slow startup times when starting a high level consumer in a low traffic/blocking fetch type setup. The example we've come across has a consumer that is set up to use 3 topics and uses a 20s/1 byte fetch timeout. What happens is that the leader finder thread adds partitions one by one and since the offset is not know this causes a call to figure out the offset. This call uses the fetcher threads simple consumer instance and locks around the call. Initially this is not a problem, but as soon as the fetcher thread has some partitions it will start fetching and since this is a low traffic situation the fetch will at least sometimes take up to 20s (again locking around the simple consumer). This leads to behavior like:
> # Finder thread adds a partition
> # Data thread notices it has partitions to fetch data for, locks the consumer for 20s
> # Finder thread tries to add a partition, tries to lock consumer and blocks for 20s
> # Rinse, repeat for each partition



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