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https://issues.apache.org/jira/browse/HDFS-10326?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15257422#comment-15257422
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He Tianyi commented on HDFS-10326:
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Some system may not support auto tuning, defaulting to a small window size (say
64k? which may make the scenario worse).
I'd suggest we keep the configuration. Or maybe add another one, say
{{dfs.socket.detect-auto-turning}}. When this is set to {{true}} (maybe turned
on by default), socket buffer behavior depends on whether OS supports
auto-tuning. If auto-tuning is not supported, use configured value
automatically.
> Disable setting tcp socket send/receive buffers for write pipelines
> -------------------------------------------------------------------
>
> Key: HDFS-10326
> URL: https://issues.apache.org/jira/browse/HDFS-10326
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: datanode, hdfs
> Affects Versions: 2.6.0
> Reporter: Daryn Sharp
> Assignee: Daryn Sharp
>
> The DataStreamer and the Datanode use a hardcoded
> DEFAULT_DATA_SOCKET_SIZE=128K for the send and receive buffers of a write
> pipeline. Explicitly setting tcp buffer sizes disables tcp stack
> auto-tuning.
> The hardcoded value will saturate a 1Gb with 1ms RTT. 105Mbs at 10ms.
> Paltry 11Mbs over a 100ms long haul. 10Gb networks are underutilized.
> There should either be a configuration to completely disable setting the
> buffers, or the the setReceiveBuffer and setSendBuffer should be removed
> entirely.
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