Mailing-List: contact mapreduce-issues-help@hadoop.apache.org; run by ezmlm
Precedence: bulk
Reply-To: mapreduce-issues@hadoop.apache.org
Message-ID: <124389516.685051270459887271.JavaMail.jira@brutus.apache.org>
Date: Mon, 5 Apr 2010 09:31:27 +0000 (UTC)
From: "Sreekanth Ramakrishnan (JIRA)" <jira@apache.org>
To: mapreduce-issues@hadoop.apache.org
Subject: [jira] Commented: (MAPREDUCE-1640) Node health feature fails to
 blacklist a node if the health check script times out in some cases
In-Reply-To: <360405353.543341269851727433.JavaMail.jira@brutus.apache.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit


    [ https://issues.apache.org/jira/browse/MAPREDUCE-1640?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12853346#action_12853346 ] 

Sreekanth Ramakrishnan commented on MAPREDUCE-1640:
---------------------------------------------------

The problem in gist: 

* In bash scripts all the commands are spawned using fork + exec. Similar to system() syscall. The process hierarchy is as follows:
{noformat}
15772 pts/0    S      0:00  \_ /bin/bash ./myscript.sh
15773 pts/0    S      0:00  |   \_ sleep 100000
{noformat}
* So when kill 15772 is sent, the signal is not delivered to child.
* So parent exits and sleep does not check if the parent is alive or not continues doing its work as it is a long running process.

The problem is similar to what is mentioned and addressed in HADOOP-2721

For this problem all the node health script which is spawned should do: {{setsid; exec(node_health_path)}} and then instead of Process.destory() we do {{kill -pid}}, now the problem is that pid of the process is now passed on to java, so it will change to {{setsid; echo $$ ;exec(node_health_path)}} and we should read the input stream to get process id.

Or alternate solution to the problem is the node health script configured manages its children  :-)

> Node health feature fails to blacklist a node if the health check script times out in some cases
> ------------------------------------------------------------------------------------------------
>
>                 Key: MAPREDUCE-1640
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-1640
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>          Components: tasktracker
>            Reporter: Vinod K V
>             Fix For: 0.22.0
>
>
> Node health check feature fails to blacklist a TT if health check script times out. Below are the values that were set:
>  - mapred.healthChecker.interval=60000
>  - mapred.healthChecker.script.timeout=6000
> And the script was:
> {code}
> #!/bin/bash
> echo "start"
> sleep 100000
> echo "end"
> {code}

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.