User:Carl Boettiger/Notebook/Comparative Phylogenetics/2010/04/22

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Adaptive Dynamics

compiling with R and C and parallel computing

  • Problem: cannot get the R code to take advantage of parallelization via openMP.
  • Solution:

C++ file mangles names in .so, changing the .C call. to get the object name: <syntaxhighlight lang="bash"> objdump -x file.so </syntaxhighlight> Carl Boettiger 03:01, 25 May 2010 (EDT): More standard solution: enclose cpp code in 

 extern C {


  • Problem: Trouble getting R to export the C library to all nodes. (Sol'n thanks to Vinh on R-sig-hpc!)
  • Also, locating the .so file in a way that is independent of package installation, needs to find the package install. (Sol'n thanks to Vince on statcompsci). (Updated on 2010-04-23).
  • Solution:

<syntaxhighlight lang="rsplus"> 

   loc <- system.file(package="BranchingTime")
   lib <- paste(loc, "/libs/BranchingTime.so", sep="")
   sfExport("lib")
   sfClusterEval(dyn.load(lib) )

</syntaxhighlight>

  • Problem Random number generator needs to be specified above the parallel computation loop. Easy to do in C, but won't work for R where the random number generator is from GSL but the parallelization is at the R level. Will need to figure out how to generate different random seeds on each thread and pass that down to the C code...
  • Solution:

Now R generates and passes a random seed to the C function. (2010-04-23).

Git Log

<syntaxhighlight lang="bash"> commit 9c4167b1943d8713ce179f48432fcb750fbda26d Author: Carl Boettiger <cboettig@gmail.com> Date: Thu Apr 22 19:03:09 2010 -0700 

   removing unused C files integrate.c png

commit 73f389abbe53eb923f1aea49bc9f110cfa5531a7 Author: Carl Boettiger <cboettig@gmail.com> Date: Thu Apr 22 19:01:52 2010 -0700 

   minor mods

commit a8ca40ef883b1dd33e1b7ab27f8a215e7c2746f9 Author: Carl Boettiger <cboettig@gmail.com> Date: Thu Apr 22 18:55:32 2010 -0700 

   Working R calls

commit 7c565bef0a378a68ce2c0a2a1ad73c6039871431 Author: Carl Boettiger <cboettig@gmail.com> Date: Thu Apr 22 15:31:10 2010 -0700 

   rng initialized in outer loop

commit 60192d74b45c64423994b451aad6a7627e2a56b8 Author: Carl Boettiger <cboettig@gmail.com> Date: Thu Apr 22 14:37:36 2010 -0700 

   streamlining parallelization

commit a4de1d11a2a9ce0179636770246707b18c8d8c06 Author: Carl Boettiger <cboettig@gmail.com> Date: Thu Apr 22 13:03:03 2010 -0700 

   reorganizing files by functions

</syntaxhighlight>


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