http://www.perlmonks.org?node_id=1043274

dds has asked for the wisdom of the Perl Monks concerning the following question:

The following command sometimes takes as much as half a minute to run under Cygwin (1-7.19-1) and perl 5, version 14, subversion 2 (v5.14.2) built for cygwin-thread-multi-64int on an otherwise idle system with 16GB of RAM and an 8-core CPU running Windows 7. 
$ time /usr/bin/perl -e 'use File::Temp'

real    0m38.796s
user    0m0.109s
sys     0m0.124s

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The second time it is executed it is typically considerably faster. 
$ time /usr/bin/perl -e 'use File::Temp'

real    0m2.498s
user    0m0.124s
sys     0m0.124s

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I have run the command under strace to see if there was a particular system call that takes a long time to execute, but a cursory examination of the output didn't show me such a culprit.

I also looked at the time when each included file is opened, and I see that they are evenly spread out, with some however (warnings, Cwd, Config, Basename, constant) taking more than a second to load. 

$ awk '/open: open/{print $2 / 1e6, $7}' strace.out

0.062687 open(/dev/urandom,
0.093652 open(/dev/urandom,
0.162175 open(/dev/null,
0.332337 open(/usr/lib/perl5/5.14/File/Temp.pm,
0.413667 open(/usr/lib/perl5/5.14/strict.pm,
0.574798 open(/usr/lib/perl5/5.14/Carp.pm,
0.647806 open(/usr/lib/perl5/5.14/warnings.pm,
2.12777 open(/usr/lib/perl5/5.14/Exporter.pm,
2.40747 open(/usr/lib/perl5/5.14/i686-cygwin-threads-64int/File/Spec.p
+m,
2.48178 open(/usr/lib/perl5/5.14/vars.pm,
2.56121 open(/usr/lib/perl5/5.14/warnings/register.pm,
2.83884 open(/usr/lib/perl5/5.14/i686-cygwin-threads-64int/File/Spec/C
+ygwin.pm,
3.06084 open(/usr/lib/perl5/5.14/i686-cygwin-threads-64int/File/Spec/U
+nix.pm,
3.59694 open(/usr/lib/perl5/5.14/File/Path.pm,
3.67258 open(/usr/lib/perl5/5.14/i686-cygwin-threads-64int/Cwd.pm,
4.72324 open(/usr/lib/perl5/5.14/XSLoader.pm,
4.94318 open(/usr/lib/perl5/5.14/i686-cygwin-threads-64int/DynaLoader.
+pm,
5.00538 open(/usr/lib/perl5/5.14/i686-cygwin-threads-64int/Config.pm,
16.219 open(/usr/lib/perl5/5.14/File/Basename.pm,
17.3896 open(/usr/lib/perl5/5.14/i686-cygwin-threads-64int/Fcntl.pm,
17.7389 open(/usr/lib/perl5/5.14/i686-cygwin-threads-64int/IO/Seekable
+.pm,
17.8311 open(/usr/lib/perl5/5.14/i686-cygwin-threads-64int/IO/Handle.p
+m,
17.9298 open(/usr/lib/perl5/5.14/Symbol.pm,
18.1662 open(/usr/lib/perl5/5.14/SelectSaver.pm,
18.2823 open(/usr/lib/perl5/5.14/i686-cygwin-threads-64int/IO.pm,
19.0989 open(/usr/lib/perl5/5.14/i686-cygwin-threads-64int/Errno.pm,
19.468 open(/usr/lib/perl5/5.14/base.pm,
19.8129 open(/usr/lib/perl5/5.14/overload.pm,
20.236 open(/usr/lib/perl5/5.14/constant.pm,
22.0238 open(/usr/lib/perl5/5.14/Carp/Heavy.pm,
22.1132 open(/usr/lib/perl5/5.14/Exporter/Heavy.pm,

[download]

Replies are listed 'Best First'.
Re: File::Temp painfully slow under Cygwin
by hdb (Monsignor) on Jul 09, 2013 at 09:29 UTC

    Is this only happening for File::Temp or other modules as well?

[reply]
[d/l]
[select]
      I had no problem with 
      use File::Copy;
use Getopt::Std;
use IO::Handle;

      [download]
[reply]
[d/l]
        Get Devel::Trace and try  perl -d:Trace -e ' require File::Temp; ' and try to find where it hangs
[reply]
[d/l]
Re: File::Temp painfully slow under Cygwin (Cygwin HD)
by Anonymous Monk on Jul 09, 2013 at 09:22 UTC

    Sounds like cygwin+harddisk issue, like not loading an *cough* UDMA driver, which can cripple a win32 system

    or some kind of cygwin induced swapping

    Tough stuff to figure out

[reply]
      The problem is indeed related to Cygwin. The ActiveState version executes the same code lightningly fast. 
      $ time /cygdrive/c/Perl/bin/perl  -e 'use File::Temp'

real    0m0.212s
user    0m0.015s
sys     0m0.015s

$ /cygdrive/c/Perl/bin/perl -v

This is perl 5, version 16, subversion 3 (v5.16.3) built for MSWin32-x
+86-multi-thread
(with 1 registered patch, see perl -V for more detail)

Copyright 1987-2012, Larry Wall

Binary build 1603 [296746] provided by ActiveState http://www.ActiveSt
+ate.com
Built Mar 13 2013 11:29:21

      [download]
[reply]
[d/l]
Re: File::Temp painfully slow under Cygwin
by Laurent_R (Canon) on Jul 09, 2013 at 18:49 UTC

    It may not help very much, but I just tried your command under Cygwin, Win 7 and 8 cores (in other words, a configuration very similar to what you have). First call and second one: 

    Laurent@Laurent-HP ~
$ time /usr/bin/perl -e 'use File::Temp'

real    0m0.763s
user    0m0.108s
sys     0m0.139s

Laurent@Laurent-HP ~
$ time /usr/bin/perl -e 'use File::Temp'

real    0m0.164s
user    0m0.093s
sys     0m0.062s

    [download]
[reply]
[d/l]
      Thank you. The problem could then be an installation issue. What do you get by running the following? 
      find /usr/lib/perl5/ -name Cwd.dll

      [download]
      In my case the file does not exist, and this may explain the problem.
[reply]
[d/l]
        My contribution from a Toshiba NB305 Netbook 1.66GHz with 2GB RAM, running WinXP: 
        $ uname -a
CYGWIN_NT-5.1 minime 1.7.20(0.266/5/3) 2013-06-07 11:11 i686 Cygwin
$ perl -v

This is perl 5, version 14, subversion 2 (v5.14.2) built for cygwin-th
+read-multi-64int
(with 7 registered patches, see perl -V for more detail)

Copyright 1987-2011, Larry Wall

<output truncated>

$ time /usr/bin/perl -e 'use File::Temp'

real    0m0.469s
user    0m0.358s
sys     0m0.125s
$ time /usr/bin/perl -e 'use File::Temp'

real    0m0.438s
user    0m0.249s
sys     0m0.202s

        [download]
        ...and the search for Cwd.dll returned nothing.

        I initially ran this earlier and the "real" time was just over two seconds, but that was the slowest it recorded.

        Hope this helps!
[reply]
[d/l]

        Does not seem to exist either.

        Laurent@Laurent-HP ~
$ find /usr/lib/perl5/ -name Cwd.dll

Laurent@Laurent-HP ~

        [download]
[reply]
[d/l]

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