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From "Sylvain Lebresne (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-8530) Query on a secondary index creates huge CPU spike + unable to trace
Date Mon, 22 Dec 2014 16:30:13 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-8530?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14255892#comment-14255892
] 

Sylvain Lebresne commented on CASSANDRA-8530:
---------------------------------------------

bq. 3.  until recently we were using a python script that does very simple selects \[...\]
All of a sudden, same queries and same process started giving the following message \[...\]
and accompanied by huge cpu spikes (load avg went from ~2 to about ~15)
bq. 4. We figured maybe it's time to upgrade, so we did to 2.1.2 - did not help.

What I get from this is that the problem was *not* triggered by the upgrade, but the upgrade
did not fix it. Which infortunately makes it a little less easy to narrow down. Are you sure
this really happened "All of a sudden"? Namely, would it be possible that the query performance
degraded over time, but you only started noticing once it started throwing you the error message
(i.e. do you actually have monitoring that shows how fast those queries were before they started
timing out?).

> Query on a secondary index creates huge CPU spike + unable to trace
> -------------------------------------------------------------------
>
>                 Key: CASSANDRA-8530
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-8530
>             Project: Cassandra
>          Issue Type: Bug
>          Components: API, Core
>         Environment: CentOs 6.5 / Cassandra 2.1.2
>            Reporter: Pavel Baranov
>
> After upgrading cassandra from 2.0.10 to 2.1.2 we are having all kinds of issues, especially
with performance.
> java version "1.7.0_65"
> Table creation:
> {noformat}
> tweets> desc table tweets;
> CREATE TABLE tweets.tweets (
>     uname text,
>     tweet_id bigint,
>     tweet text,
>     tweet_date timestamp,
>     tweet_date_only text,
>     uid bigint,
>     PRIMARY KEY (uname, tweet_id)
> ) WITH CLUSTERING ORDER BY (tweet_id ASC)
>     AND bloom_filter_fp_chance = 0.01
>     AND caching = '{"keys":"ALL", "rows_per_partition":"NONE"}'
>     AND comment = ''
>     AND compaction = {'min_threshold': '10', 'class': 'org.apache.cassandra.db.compaction.SizeTieredCompactionStrategy',
'max_threshold': '32'}
>     AND compression = {'sstable_compression': 'org.apache.cassandra.io.compress.LZ4Compressor'}
>     AND dclocal_read_repair_chance = 0.0
>     AND default_time_to_live = 0
>     AND gc_grace_seconds = 864000
>     AND max_index_interval = 2048
>     AND memtable_flush_period_in_ms = 0
>     AND min_index_interval = 128
>     AND read_repair_chance = 0.1
>     AND speculative_retry = '99.0PERCENTILE';
> CREATE INDEX tweets_tweet_date_only_idx ON tweets.tweets (tweet_date_only);
> CREATE INDEX tweets_uid ON tweets.tweets (uid);
> {noformat}
> With Cassandra 2.0.10 this query:
> {noformat}
> select uname from tweets where uid = 636732672 limit 1;
> {noformat}
> did not have any issues. After upgrade, I can see the cpu spikes and load avg goes from
~1 to ~13, especially if I execute the query over and over again.
> Doing "tracing on" does not work and just returns: 
> "Statement trace did not complete within 10 seconds"
> I've done:
> nodetool upgradesstables
> recreated indexes



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