Great! Glad to see that it works and has perceivable speed-up. Best, Yixuan On Nov 23, 2014 10:57 PM, "Justace Clutter" <justa...@gmail.com> wrote:
> I would say that was it... Thanks for catching that. Sometimes the > smallest thing can get you. I have updated the SO question with the answer. > > Now that I got this working I am seeing great speed improvements: > > b1 = R native code > b2 = Rcpp non parallel > b3 = Rcpp parallel > > test replications elapsed relative user.self sys.self user.child > sys.child > 1 b1() 10 1760.65 78.776 1753.76 0.56 NA > NA > 2 b2() 10 128.78 5.762 128.38 0.05 NA > NA > 3 b3() 10 22.35 1.000 170.68 0.06 NA > NA > > > On Sun, Nov 23, 2014 at 9:15 PM, Yixuan Qiu <yixuan....@cos.name> wrote: > >> Hello Justace, >> It seems that you should write down j < end rather than j <= end. >> >> >> Best, >> Yixuan >> >> 2014-11-23 21:10 GMT-05:00 Justace Clutter <justa...@gmail.com>: >> >>> I posted the following to SO earlier this morning and it was suggested >>> that I repost this question to the rcpp-devel list for exposure. For >>> reference, the original posting is at >>> http://stackoverflow.com/questions/27089888/rcppparallel-example-crashing-r >>> . >>> >>> I have been trying to parallelize one of my Rcpp routines. In doing so >>> I have been trying to follow the [Parallel Distance Calculation]( >>> http://gallery.rcpp.org/articles/parallel-distance-matrix/) example >>> from jjalaire. Unfortunately, once I got everything coded up and started >>> to play around, my R session would crash. Sometimes after the first >>> execution, sometimes after the third. To be honest, it was a crap shoot as >>> to when R would crash when I ran the routine. So, I have paired down my >>> code to a small reproducible example to play with. >>> >>> ***Rcpp File (mytest.cpp)*** >>> >>> ------------------------------------------------------------------------------------------------------------ >>> #include <Rcpp.h> >>> // [[Rcpp::depends(RcppParallel)]] >>> #include <RcppParallel.h> >>> >>> using namespace std; >>> using namespace Rcpp; >>> using namespace RcppParallel; >>> >>> struct MyThing : public Worker { >>> RVector<double> _pc; >>> RVector<double> _pcsd; >>> >>> MyThing(Rcpp::NumericVector _pc, Rcpp::NumericVector _pcsd) : >>> _pc(_pc), _pcsd(_pcsd){} >>> >>> void operator()(std::size_t begin, std::size_t end) { >>> >>> for(int j = begin; j <= end; j++) { >>> _pc[j] = 1; >>> // _pcsd[j] = 1; >>> } >>> } >>> }; >>> >>> // [[Rcpp::export]] >>> void calculateMyThingParallel() { >>> >>> NumericVector _pc(100); >>> NumericVector _pcsd(100); >>> >>> MyThing mt(_pc, _pcsd); >>> >>> parallelFor(0, 100, mt); >>> } >>> >>> ------------------------------------------------------------------------------------------------------------ >>> >>> >>> ***R Compilation and Execution Script (mytest.R)*** >>> >>> ------------------------------------------------------------------------------------------------------------ >>> library(Rcpp) >>> library(inline) >>> >>> sourceCpp('mytest.cpp') >>> >>> testmything = function() { >>> calculateMyThingParallel() >>> } >>> >>> if(TRUE) { >>> for(i in 1:20) { >>> testmything() >>> } >>> } >>> >>> ------------------------------------------------------------------------------------------------------------ >>> >>> The error seems to be directly related to my setting of the _pc and >>> _pcsd variables in the `operator()` method. If I take those out things >>> dramatically improve. Based on the Parallel Distance Calculation example, >>> I am not sure what it is that I have done wrong here. I was under the >>> impression that RVector<type> was thread safe. Although that is my >>> impression, I know this is an issue with threads somehow. Can anybody help >>> me to understand why the above code randomly crashes my R sessions? >>> >>> For information I am running the following: >>> >>> - Windows 7 >>> - R: 3.1.2 >>> - Rtools: 3.1 >>> - Rcpp: 0.11.3 >>> - inline: 0.3.13 >>> - RStudio: 0.99.62 >>> >>> >>> _______________________________________________ >>> Rcpp-devel mailing list >>> Rcpp-devel@lists.r-forge.r-project.org >>> https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel >>> >> >> >> >> -- >> Yixuan Qiu <yixuan....@cos.name> >> Department of Statistics, >> Purdue University >> > >
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