From: A.J. Rossini (rossini@blindglobe.net)
Date: Wed 17 Apr 2002 - 07:21:09 EST
Message-id: <87sn5v7322.fsf@jeeves.blindglobe.net>
>>>>> "timothy" == Timothy H Keitt <tklistaddr@keittlab.bio.sunysb.edu> writes:
timothy> On Tue, 2002-04-16 at 11:22, ripley@stats.ox.ac.uk wrote:
>> Careful! They are running (arbitrary) R code, and Luke's caveats apply.
>> Internally lapply does an eval(), and we can't have more than one of
>> those running at once without all the perils of user R-level threads,
>> as I understand it.
timothy> Ah, yes, I see the problem there. Sounds like the rpvm version might be
timothy> interesting though. In practice, most of the problems I work on are of
timothy> the 'embarrassingly parallel' variety -- running the same code with
timothy> different parameters -- and wouldn't really benefit much from low-level
timothy> parallelism. For those, I've found that having a process query a
timothy> database for parameter sets, compute a result and then write the result
timothy> back to the database before proceeding to the next parameter set works
timothy> well. You get automatic load balancing and can query the database for
timothy> intermediate results. Maybe I'll package that up for general consumption
timothy> at some point.
While RPVM is annoying to setup, I should mention that features that
we are working for "Release Soon"(tm), are
1. use of the SPRNG library, as a separate package (this is a parallel
RNG, which gives reasonable results and is designed for parallel
situations). This might be useful in other contexts as well
2. simple examples for bootstrap.
I should note that someone (to remain nameless) has offered to provide
a means to serialize R objects sensibly. We'll see when that happens;
it's simple provided that you program carefully. However, I'd like a
variant which is simple even when you are a programming klutz.
I'd also like to construct simple examples for simple global
optimization as well as MCMC, but I don't see doing these personally
in the near-ish future.
In addition, note that PVM jobs migrate on MOSIX/OpenMOSIX. I've
preliminary evidence that this is true for RPVM jobs, as well (since
Python is problematic under MOSIX, I'm not going to claim more than
preliminary evidence).
best,
-tony
-- A.J. Rossini Rsrch. Asst. Prof. of Biostatistics U. of Washington Biostatistics rossini@u.washington.edu FHCRC/SCHARP/HIV Vaccine Trials Net rossini@scharp.org -------------- http://software.biostat.washington.edu/ ---------------- FHCRC: M-W: 206-667-7025 (fax=4812)|Voicemail is pretty sketchy/use Email UW: Th: 206-543-1044 (fax=3286)|Change last 4 digits of phone to FAX (my friday location is usually completely unpredictable.)-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request@stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._
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