Adding a combiner step first then reduce?
On Feb 8, 2013, at 11:18 PM, Harsh J <[email protected]> wrote: > Hey David, > > There's no readily available way to do this today (you may be > interested in MAPREDUCE-199 though) but if your Job scheduler's not > doing multiple-assignments on reduce tasks, then only one is assigned > per TT heartbeat, which gives you almost what you're looking for: 1 > reduce task per node, round-robin'd (roughly). > > On Sat, Feb 9, 2013 at 9:24 AM, David Parks <[email protected]> wrote: >> I have a cluster of boxes with 3 reducers per node. I want to limit a >> particular job to only run 1 reducer per node. >> >> >> >> This job is network IO bound, gathering images from a set of webservers. >> >> >> >> My job has certain parameters set to meet “web politeness” standards (e.g. >> limit connects and connection frequency). >> >> >> >> If this job runs from multiple reducers on the same node, those per-host >> limits will be violated. Also, this is a shared environment and I don’t >> want long running network bound jobs uselessly taking up all reduce slots. > > > > -- > Harsh J > Michael Segel | (m) 312.755.9623 Segel and Associates
