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set TMPDIR variable to soft link pointing to PWD #21419

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merged 4 commits into from
Nov 24, 2017
Merged

set TMPDIR variable to soft link pointing to PWD #21419

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32e9981
set TMPDIR variable to soft link pointing to PWD
Nov 21, 2017
7269afc
apply code-checks
Nov 21, 2017
8eaf958
replace TMPDIR with its content
Nov 21, 2017
b932324
Update SherpackUtilities.cc
Nov 23, 2017
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8 changes: 8 additions & 0 deletions GeneratorInterface/SherpaInterface/src/SherpackUtilities.cc
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Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
#include "GeneratorInterface/SherpaInterface/interface/SherpackUtilities.h"
#include <unistd.h>
#include <cstdlib>
namespace spu {

// functions for inflating (and deflating)
Expand Down Expand Up @@ -153,6 +154,13 @@ void zerr(int ret)
/* compress or decompress from stdin to stdout */
int Unzip(std::string infile, std::string outfile)
{
std::string tmpdir = getenv("TMPDIR");
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hi @perrozzi - could we follow @bbockelm guidance here and first check the size of tmpdir. it seems the maximum total length is 108 for the path - so the check should be just like if (tmpdir.size() > 50 ) { ...} [probably you know better than I how long the sherpa part of that path is going to be ..]

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I expect the Sherpa directories to be O(10) chars, cfr https://hypernews.cern.ch/HyperNews/CMS/get/edmFramework/3807/1/1/1.html
I will put >50 just to be on the safe side

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There is no guarantee that $TMPDIR is set, meaning that getenv could result in a nullptr.

if (tmpdir.size() > 50 ){
std::string command = "ln -s $PWD "+tmpdir+"/tmp;";
system(command.c_str());
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This does not check if system returns a failure value.

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I put printouts and confirm that things get created properly

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A few things to consider in addition to Chris's comment:

  • What happens if this path already exists (but is owned by someone else)?
  • What happens if $TMPDIR is not unique to the job (several jobs run in the same directory, potentially owned by different users)?
  • What happens if $PWD contains spaces or special characters in it?
  • Who cleans up this symlink when the job finishes?

As written, if there's a shared $TMPDIR with a long name, one job will run successfully and then all subsequent ones on the worker node will fail.

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@Dr15Jones @bbockelm investigating a bit further I came across this
https://www.open-mpi.org/faq/?category=osx#startup-errors-with-open-mpi-2.0.x
and the conclusion is:
The workaround for the Open MPI 2.0.x and v2.1.x release series is to set the TMPDIR environment variable to /tmp or other short directory name.
as far as I see from the example, the directory created in the TMPDIR path should be unique and related to the MPI session.
Would it be an acceptable solution to assing /tmp/ or /tmp/$USER/ as TMPDIR value in SherpackUtilities.cc? I don't see how we could move forward otherwise. Thanks a lot

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@perrozzi perrozzi Dec 11, 2017 •
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most important, the written data seems to be cleaned up by MPI after use (i.e. if I point TMPDIR to any directory, it is empty after the job has either succeeded or failed)

command = tmpdir+"/tmp";
setenv("TMPDIR",command.c_str(), true);
}
int ret;
FILE *in = fopen(infile.c_str(),"r");
if (!in) return -1;
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