[jira] [Created] (CASSANDRA-5534) Writing wide row causes high CPU usage after compaction

["Ryan McGuire (JIRA)" <ji...@apache.org>]

Ryan McGuire created CASSANDRA-5534:
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             Summary: Writing wide row causes high CPU usage after compaction
                 Key: CASSANDRA-5534
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-5534
             Project: Cassandra
          Issue Type: Bug
    Affects Versions: 2.0
            Reporter: Ryan McGuire
            Assignee: Jonathan Ellis


Introduced in commit e74c13ff08663d306dcc5cdc99c07e9e6c12ca21 there is a significant slow down when creating a wide row with cassandra-stress:

Testing with the prior (good) commit I used this to write a single wide row, which completed rather quickly:
{code}
$ ccm create -v git:60f09f0121e0801851b9ab017eddf7e326fa05fb wide-row
Fetching Cassandra updates...
Cloning Cassandra (from local cache)
Checking out requested branch (60f09f0121e0801851b9ab017eddf7e326fa05fb)
Compiling Cassandra 60f09f0121e0801851b9ab017eddf7e326fa05fb ...
Current cluster is now: wide-row
$ ccm populate -n 1
$ ccm start
$ time ccm node1 stress -c 10000 -S 1000 -n 1
Created keyspaces. Sleeping 1s for propagation.
total,interval_op_rate,interval_key_rate,latency/95th/99th,elapsed_time
1,0,0,273.3,273.3,273.3,0
END

real	0m7.106s
user	0m1.710s
sys	0m0.120s
{code}

Using the bugged commit (e74c13ff08663d306dcc5cdc99c07e9e6c12ca21) I get a significant slow down:
{code}
02:42 PM:~$ ccm create -v git:e74c13ff08663d306dcc5cdc99c07e9e6c12ca21 wide-row
Fetching Cassandra updates...
Current cluster is now: wide-row
02:42 PM:~$ ccm populate -n 1
02:42 PM:~$ ccm start
02:42 PM:~$ time ccm node1 stress -c 10000 -S 1000 -n 1
Created keyspaces. Sleeping 1s for propagation.
total,interval_op_rate,interval_key_rate,latency,95th,99th,elapsed_time
1,0,0,423.2,423.2,423.2,0
Total operation time      : 00:00:00
END

real	4m16.394s
user	0m2.230s
sys	0m0.137s

{code}

Interestingly, the commit in question just says it's a merge from cassandra-1.2, but I do not see this same slowdown using that branch, this only occurs in trunk.

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