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From "Philip (flip) Kromer (JIRA)" <j...@apache.org>
Subject [jira] Commented: (CASSANDRA-1434) ColumnFamilyOutputFormat performs blocking writes for large batches
Date Mon, 30 Aug 2010 07:31:53 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-1434?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12904098#action_12904098
] 

Philip (flip) Kromer commented on CASSANDRA-1434:
-------------------------------------------------

The blocking behavior is causing 'broken pipe' errors (even with relatively small batch sizes)
when cassandra latency is high. 

It also makes the whole cluster resonate: one slow node blocks many writers, which then all
unblock at the same time, write bursts of enough size to cause a compaction or GC, etc simultaneously
on every node. This means adding more writers doesn't work around the blocking write

> ColumnFamilyOutputFormat performs blocking writes for large batches
> -------------------------------------------------------------------
>
>                 Key: CASSANDRA-1434
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-1434
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Hadoop
>            Reporter: Stu Hood
>             Fix For: 0.7.0
>
>
> By default, ColumnFamilyOutputFormat batches {{mapreduce.output.columnfamilyoutputformat.batch.threshold}}
or {{Long.MAX_VALUE}} mutations, and then performs a blocking write.

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