[jira] [Updated] (CASSANDRA-5466) Compaction task eats 100% CPU for a long time for tables with collection typed columns

["Alex Zarutin (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CASSANDRA-5466?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Alex Zarutin updated CASSANDRA-5466:
------------------------------------

    Assignee: Alex Zarutin  (was: Ryan McGuire)
    
> Compaction task eats 100% CPU for a long time for tables with collection typed columns
> --------------------------------------------------------------------------------------
>
>                 Key: CASSANDRA-5466
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-5466
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>    Affects Versions: 1.2.4
>         Environment: ubuntu 12.10, sun-6-java 1.6.0.37, Core-i7, 8GB RAM
>            Reporter: Alexey Tereschenko
>            Assignee: Alex Zarutin
>
> For the table:
> {code:sql}
> create table test (
>         user_id bigint,
>         first_list list<bigint>,
>         second_list list<bigint>,
>         third_list list<bigint>,
>         PRIMARY KEY (user_id)
> );
> {code}
> I do thousands of updates like the following:
> {code:sql}
> UPDATE test SET first_list = [1], second_list = [2], third_list = [3] WHERE user_id = ?;
> {code}
> In several minutes a compaction task starts running. {{nodetool compactionstats}} shows that remaining time is 2 seconds but in fact it can take hours to really complete the compaction tasks. And during that time Cassandra consumes 100% of CPU and slows down so significally that it gives connection timeout exceptions to any client code trying to establish connection with Cassandra. This happens only with tables with collection typed columns.

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