[
https://issues.apache.org/jira/browse/HDFS-3898?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13450904#comment-13450904
]
Todd Lipcon commented on HDFS-3898:
-----------------------------------
Right, Nagle's algorithm applies to all packets. But the bad
(40ms-latency-causing) interaction between Nagle's Algorithm and Delayed ACK
only applies when you have an even number of packets in a message (I think? or
is it odd? it's complicated and I can't ever remember). The following page
(coincidentally by the author of my favorite computer game ever) is pretty good
at describing the issue: http://www.stuartcheshire.org/papers/NagleDelayedAck/
> QJM: enable TCP_NODELAY for IPC
> -------------------------------
>
> Key: HDFS-3898
> URL: https://issues.apache.org/jira/browse/HDFS-3898
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Affects Versions: QuorumJournalManager (HDFS-3077)
> Reporter: Todd Lipcon
> Assignee: Todd Lipcon
> Priority: Blocker
> Attachments: hdfs-3898.txt
>
>
> Currently, if the size of the edits batches is larger than the MTU, it can
> result in 40ms delays due to interaction between nagle's algorithm and
> delayed ack. Enabling TCP_NODELAY on the sockets solves this issue, so we
> should set those configs by default for all of the QJM-related IPC.
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira
