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https://issues.apache.org/jira/browse/CASSANDRA-5466?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13733028#comment-13733028
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Alex Zarutin commented on CASSANDRA-5466:
-----------------------------------------
Tested on latest Cassandra-1.2 (1.2.8) using the reproduction steps attached:
Short time CPU peak during the compaction task running:
Wed Aug 7 17:56:36 PDT 2013
pending tasks: 1
compaction type keyspace column family completed
total unit progress
Compaction Keyspace1 test 88704036
143494491 bytes 61.82%
Active compaction remaining time : 0h00m03s
After which CPU came back to zero.
Number of the writes: ~ 1.8M:
$ /Users/alexzarutin/.ccm/repository/1.2.4/bin/nodetool --host localhost
--port 7100 cfstats | grep -A 10 'Keyspace1'
Keyspace: Keyspace1
Read Count: 0
Read Latency: NaN ms.
Write Count: 1783789
Write Latency: 0.15905207005985575 ms.
Pending Tasks: 0
Column Family: Counter1
SSTable count: 0
Space used (live): 0
Space used (total): 0
Number of Keys (estimate): 0
> 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
> Attachments: CASSANDRA-5466.txt, Cassandra_JDBC_Updater.tar.gz,
> logs-system-cass-5466-output-30-threads-1386752-req-Default-LCS.log,
> logs-system-cass-5466-output-30-threads-1578752-req-LeveledCompactionStrategy.log,
>
> nodetool-compactionstats-cass-5466-output-30-threads-1386752-req-Default-LCS.log,
>
> nodetool-compactionstats-cass-5466-output-30-threads-1578752-req-LeveledCompactionStrategy.log
>
>
> 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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