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MapReduce >> mail # user >> What happens to blacklisted TaskTrackers?

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RE: What happens to blacklisted TaskTrackers?
Hi Pedro,

1. If the Tast Tracker doesn't send heart beat for some time(i.e expiry interval), the the task tracker will be declared as lost tracker and not black listed task tracker. If many tasks are failing in the same Task Tracker for a job, then the TT will be black listed for job, if it happens for many jobs then the TT will be black listed for all jobs.

2. There will not be any problem for previoulsy launched tasks if those were completed successfully. It will not launch any more new tasks after blacklisting.

3. The task Tracker will continue sending heart beat to the Job Tracker and JT will not assign any new tasks to the blacklisted trackers.



From: Pedro Costa [[EMAIL PROTECTED]]
Sent: Thursday, April 26, 2012 3:35 PM
To: mapreduce-user
Subject: What happens to blacklisted TaskTrackers?


I've question about what happens to blacklisted TaskTracker.

1 - When a TaskTracker don't send heartbeat messages to the JobTracker for a while, it will be blacklisted. But, this means that the TaskTracker won't launch more task anymore?

2 - What happen to the tasks previously launched by the blacklisted TaskTracker? This included finished and unfinished tasks.

3 - If the TaskTracker starts to send again Heartbeats, this means the component is able to launch again the tasks?

Best regards,