hadoop-mapreduce-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Robert Kanter (JIRA)" <j...@apache.org>
Subject [jira] [Created] (MAPREDUCE-4963) StatisticsCollector improperly keeps track of "Last Day" and "Last Hour" statistics for new TaskTrackers
Date Sat, 26 Jan 2013 03:19:12 GMT
Robert Kanter created MAPREDUCE-4963:
----------------------------------------

             Summary: StatisticsCollector improperly keeps track of "Last Day" and "Last Hour"
statistics for new TaskTrackers
                 Key: MAPREDUCE-4963
                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-4963
             Project: Hadoop Map/Reduce
          Issue Type: Bug
          Components: mrv1
    Affects Versions: 1.1.1
            Reporter: Robert Kanter
            Assignee: Robert Kanter


The StatisticsCollector keeps track of updates to the "Total Tasks Last Day", "Succeed Tasks
Last Day", "Total Tasks Last Hour", and "Succeeded Tasks Last Hour" per Task Tracker which
is displayed on the JobTracker web UI.  It uses buckets to manage when to shift task counts
from "Last Hour" to "Last Day" and out of "Last Day".  After the JT has been running for a
while, the connected TTs will have the max number of buckets and will keep shifting them at
each update.  If a new TT connects (or an old on rejoins), it won't have the max number of
buckets, but the code that drops the buckets uses the same counter for all sets of buckets.
 This means that new TTs will prematurely drop their buckets and the stats will be incorrect.
 

example:
# Max buckets is 5
# TaskTracker A has these values in its buckets [4, 2, 0, 3, 10] (i.e. 19)
# A new TaskTracker, B, connects; it has nothing in its buckets: [ ] (i.e. 0)
# TaskTracker B runs 3 tasks and TaskTracker A runs 5
# An update occurs
# TaskTracker A has [2, 0, 3, 10, 5] (i.e. 20)
# TaskTracker B should have [3] but it will drop that bucket after adding it during the update
and instead have [ ] again (i.e. 0)
# TaskTracker B will keep doing that forever and always show 0 in the web UI

We can fix this by not using the same counter for all sets of buckets

--
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

Mime
View raw message