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Date: Mon, 17 Mar 2008 15:46:24 -0700 (PDT)
From: "Raghu Angadi (JIRA)" <jira@apache.org>
To: core-dev@hadoop.apache.org
Subject: [jira] Commented: (HADOOP-2188) RPC should send a ping rather than
 use client timeouts
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    [ https://issues.apache.org/jira/browse/HADOOP-2188?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12579652#action_12579652 ] 

Raghu Angadi commented on HADOOP-2188:
--------------------------------------

I am looking at the patch too.. though still not done. Couple of queries :

# Why does the patch remove purging the connections on server if server is not able to write to the socket? 
# minor : in one place have '{{do { wait(); } while (!cond);}}' its unconventional in the sense, normally the right thing to do is to check for condition before waiting. 

> RPC should send a ping rather than use client timeouts
> ------------------------------------------------------
>
>                 Key: HADOOP-2188
>                 URL: https://issues.apache.org/jira/browse/HADOOP-2188
>             Project: Hadoop Core
>          Issue Type: Improvement
>          Components: dfs, ipc
>            Reporter: Owen O'Malley
>            Assignee: Hairong Kuang
>         Attachments: ipc-timeout.patch, ipc-timeout1.patch, ipc-timeout2.patch, ipc-timeout3.patch, rpc-to.patch
>
>
> Current RPC (really IPC) relies on client side timeouts to find "dead" sockets. I propose that we have a thread that once a minute (if the connection has been idle) writes a "ping" message to the socket. The client can detect a dead socket by the resulting error on the write, so no client side timeout is required. Also note that the ipc server does not need to respond to the ping, just discard it.

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