Hadoop can set the maximum mappers and reducers running on a node but under
0.20.2 I do not see a way to limit
the system from running mappers and reducers together with the total
exceeding individual limits.
I find that when my mappers are about 50% done the system kicks off
reducers. I have raised the maxmemory in
chilld.java,vm.opts because I have been hitting GC limits and the values
work well when I am running 6 mappers OR
6 reducers but when my mappers are half way done I see 6 mappers AND 6
reducers running and this challenges the
total memory on a node.
How can I keep the total tasks on a node under control without limiting the
maximum mappers and reducers to half the total I want??
Steven M. Lewis PhD
4221 105th Ave NE
Kirkland, WA 98033