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Date: Mon, 30 Aug 2010 05:39:53 -0400 (EDT)
From: "Philip (flip) Kromer (JIRA)" <jira@apache.org>
To: commits@cassandra.apache.org
Subject: [jira] Issue Comment Edited: (CASSANDRA-1434)
 ColumnFamilyOutputFormat performs blocking writes for large batches
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    [ https://issues.apache.org/jira/browse/CASSANDRA-1434?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12904098#action_12904098 ] 

Philip (flip) Kromer edited comment on CASSANDRA-1434 at 8/30/10 5:38 AM:
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The blocking behavior is causing 'broken pipe' errors (even with relatively small batch sizes) when cassandra latency is high. (This is afaict not network latency but response latency due to a compaction or flush, etc.)

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

      was (Author: mrflip):
    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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