Dear R-devel, I am running mclapply with many iterations over a function that modifies nothing and makes no copies of anything. It is taking up a lot of memory, so it seems to me like this is a bug. Should I post this to bugs.r-project.org?
A minimal reproducible example can be obtained by first starting a memory monitoring program such as htop, and then executing the following code while looking at how much memory is being used by the system library(parallel) seconds <- 5 N <- 100000 result.list <- mclapply(1:N, function(i)Sys.sleep(1/N*seconds)) On my system, memory usage goes up about 60MB on this example. But it does not go up at all if I change mclapply to lapply. Is this a bug? For a more detailed discussion with a figure that shows that the memory overhead is linear in N, please see https://github.com/tdhock/mclapply-memory > sessionInfo() R version 3.2.2 (2015-08-14) Platform: x86_64-pc-linux-gnu (64-bit) Running under: Ubuntu precise (12.04.5 LTS) locale: [1] LC_CTYPE=en_CA.UTF-8 LC_NUMERIC=C [3] LC_TIME=en_US.UTF-8 LC_COLLATE=en_CA.UTF-8 [5] LC_MONETARY=en_US.UTF-8 LC_MESSAGES=en_CA.UTF-8 [7] LC_PAPER=en_US.UTF-8 LC_NAME=C [9] LC_ADDRESS=C LC_TELEPHONE=C [11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C attached base packages: [1] parallel graphics utils datasets stats grDevices methods [8] base other attached packages: [1] ggplot2_1.0.1 RColorBrewer_1.0-5 lattice_0.20-33 loaded via a namespace (and not attached): [1] Rcpp_0.11.6 digest_0.6.4 MASS_7.3-43 [4] grid_3.2.2 plyr_1.8.1 gtable_0.1.2 [7] scales_0.2.3 reshape2_1.2.2 proto_1.0.0 [10] labeling_0.2 tools_3.2.2 stringr_0.6.2 [13] dichromat_2.0-0 munsell_0.4.2 PeakSegJoint_2015.08.06 [16] compiler_3.2.2 colorspace_1.2-4 [[alternative HTML version deleted]] ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
