hadoop-common-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From 我的Gmail邮箱 <zhangxiang...@gmail.com>
Subject why reduce task can be scheduled before map tasks are 100% completed?
Date Sun, 02 Aug 2009 12:02:24 GMT
Hi, everyone.
In class org.apache.hadoop.mapred.JobInProgress, there is a public method:
scheduleReduces(), it will return true if "finishedMapTasks >=
completedMapsForReduceSlowstart"
and then the scheduler can schedule a new reduce task for a given
taskTracker.

but as I konw, reduce can not be started unitl map is 100% completed. Does
anyone can explain it? thanks a lot.

Mime
  • Unnamed multipart/alternative (inline, None, 0 bytes)
View raw message