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From "Ramzi Rabah (JIRA)" <j...@apache.org>
Subject [jira] Commented: (CASSANDRA-646) Fix few minor problems in nodeprobe cfstats
Date Sun, 20 Dec 2009 16:18:18 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-646?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12792999#action_12792999
] 

Ramzi Rabah commented on CASSANDRA-646:
---------------------------------------

Fair enough. Should I log a separate enhancement to log the TimedOutException in the SP side,
and leave this bug to fix NaN for a Keyspace in the presence of multiple cfs?

> Fix few minor problems in nodeprobe cfstats
> -------------------------------------------
>
>                 Key: CASSANDRA-646
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-646
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Tools
>    Affects Versions: 0.5
>            Reporter: Ramzi Rabah
>            Priority: Minor
>
> nodeprobe cfstats reports that readlatency/writelatency is NaN on the keyspace level
although it obviously is not.
> For example:
> Keyspace: Keyspace1
>         Read Count: 392
>         Read Latency: NaN ms.
>         Write Count: 262
>         Write Latency: NaN ms.
>         Pending Tasks: 0
>                 Column Family: MyCF
>                 Memtable Columns Count: 143
>                 Memtable Data Size: 123433
>                 Memtable Switch Count: 2
>                 Read Count: 392
>                 Read Latency: 0.533 ms.
>                 Write Count: 262
>                 Write Latency: 0.000 ms.
>                 Pending Tasks: 0
>                 Column Family: Standard2
>                 Memtable Columns Count: 0
>                 Memtable Data Size: 0
>                 Memtable Switch Count: 0
>                 Read Count: 0
>                 Read Latency: NaN ms.
>                 Write Count: 0
>                 Write Latency: NaN ms.
>                 Pending Tasks: 0
> The problem here is that there is more than one cf, and one of them has read latency/writelatency
NaN. This causes the keyspace readlatency/writelatency to be NaN instead of the average across
all cfs. 
> Another problem with cfstats is that it does not account for the delays when a read/write
times out, so it does not accurately reflect the health of the system under too much stress.


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