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Hadoop: mapreduce.jobtracker.expire.trackers.interval no effect

+2 votes
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we want to set the heartbeat timout for a tasktracker.

If the tasktracker does not send heartbeats for 60 seconds he should be marked as lost. I found the parameter mapreduce.jobtracker.expire.trackers.interval which sounds right to me.

I defined 

mapreduce.jobtracker.expire.trackers.interval 60000

in the mapred-site.xml on all servers and restarted the jobtracker and all tasktrackers.

I started a benchmark "hadoop jar hadoop-examples.jar randomwriter rand" and every tasktracker gets 2 jobs. It is a small test environment.

On one tasktracker i stopped the network. On the jobtracker i could see the "Seconds since heartbeat"
increasing. But after 60 seconds the tasktracker was still in the overview. Even in the log of the jobtracker I found nothing.

After over 600 seconds i found the message

org.apache.hadoop.mapred.JobTracker: Lost tracker .....

And the tasktracker wasn't shown any more on the jobtracker. Isn't this the right setting?

posted Dec 3, 2013 by Jagan Mishra

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We use Cloudera 2.0.0-mr1-cdh4.2.0
commented Dec 3, 2013 by anonymous

1 Answer

+2 votes

I did a small test, and I a setting mapred.tasktracker.expiry.interval=60000 worked for me (TT became considered as lost after around 66 seconds).

May be the formula: mapred.tasktracker.expiry.interval + 2 * some-heartbeat-interval-that-is-3-sec-by-default? Otherwise, is the 6 sec some kind of time needed to make a decision to consider TT as lost?

answer Dec 3, 2013 by Ahmed Patel
I think I have found the reason. I looked at the job.xml and found the parameter
mapred.tasktracker.expiry.interval 6000000
and
mapreduce.jobtracker.expire.trackers.interval 30000

So I tried the deprecated parameter mapred.tasktracker.expiry.interval in my configuration and it works!

Why they write that the parameter is deprecated when the new one is not working and will be overwritten by the old one with the default value?
commented Dec 4, 2013 by anonymous
I tried the deprecated parameter mapred.tasktracker.expiry.interval in my configuration and it worked...
commented Dec 5, 2013 by anonymous
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