From nakama at ki.rim.or.jp  Sat Dec  6 07:22:24 2014
From: nakama at ki.rim.or.jp (Ei-ji Nakama)
Date: Sat, 6 Dec 2014 15:22:24 +0900
Subject: [Rd] does parLapplyLB do load-balancing?
In-Reply-To: <CAG=M9LrfOFMp0wT1rR3n7sumsNrscGBDS-8bkdzOXS=45jV9KQ@mail.gmail.com>
References: <CAG=M9LrfOFMp0wT1rR3n7sumsNrscGBDS-8bkdzOXS=45jV9KQ@mail.gmail.com>
Message-ID: <CAJqeyYY8GWd1vPpG_=PGS_oKWedOENUz+c5tRpoE4Q2f_MHPyw@mail.gmail.com>

Hello,

In such cases, try the Rhpc package.

The following is the result of the benchmark.
http://prs.ism.ac.jp/~nakama/Rhpc/#benchmark

# but tuning is not finished...


2014-12-06 10:36 GMT+09:00 Chris Paciorek <paciorek at stat.berkeley.edu>:
> Looking at parLapplyLB, one sees that it takes in X and then passes
> splitList(X, length(cl)) to clusterApplyLB, which then calls
> dynamicClusterApply.  Thus while dynamicClusterApply does handle tasks
> in a load-balancing fashion, sending out individual tasks as previous
> tasks complete, parLapplyLB preempts that by splitting up the tasks in
> advance into as many groups of tasks as there are cluster processes.
> This seems to defeat the purpose of load-balancing and of the manner
> in which dynamicClusterApply is coded.
>
> This question basically repeats a question posed in 2013 -- see
> http://r.789695.n4.nabble.com/parLapplyLB-Load-balancing-tt4671848.html
>
> I'm reposting because there doesn't seem to have been any response to
> the previous posting, and it looks like the issue is still present in
> R 3.1 so it seems asking again if this is the intended behavior of
> parLapplyLB.
>
> I'm using R 3.1.1 and the 3.1.1 version of the parallel package under
> Ubuntu 14.04, but the code appears to be the same in R-devel.
>
>
> Chris
>
>
> ----------------------------------------------------------------------------------------------
> Chris Paciorek
>
> Statistical Computing Consultant
> Statistical Computing Facility, Econometrics Laboratory, Berkeley
> Research Computing
>
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-- 
Best Regards,
--
Eiji NAKAMA <nakama (a) ki.rim.or.jp>
"\u4e2d\u9593\u6804\u6cbb"  <nakama (a) ki.rim.or.jp>



[Rd] does parLapplyLB do load-balancing?
Ei-ji Nakama