Devel::GraphVizProf(3)                     User Contributed Perl Documentation


NAME
       Devel::GraphVizProf - per-line Perl profiler (with graph output)

SYNOPSIS
               perl -d:GraphVizProf test.pl > test.dot
               dot -Tpng test.dot > test.png

DESCRIPTION
       NOTE: This module is a hack of Devel::SmallProf by Ted Ashton. It has
       been modified by Leon Brocard to produce output for GraphViz, but
       otherwise the only thing I have done is change the name. I hope to get
       my patches put into the main Devel::SmallProf code eventually, or
       alternatively read the output of Devel::SmallProf. Anyway, the normal
       documentation, which you can probably ignore, follows.

       The Devel::GraphVizProf profiler is focused on the time taken for a
       program run on a line-by-line basis.  It is intended to be as "small"
       in terms of impact on the speed and memory usage of the profiled
       program as possible and also in terms of being simple to use.  Those
       statistics are placed in the file smallprof.out in the following
       format:

               <num> <time> <ctime> <line>:<text>

       where <num> is the number of times that the line was executed, <time>
       is the amount of "wall time" (time according the the clock on the wall
       vs. cpu time) spent executing it, <ctime> is the amount of cpu time
       expended on it and <line> and <text> are the line number and the actual
       text of the executed line (read from the file).

       The package uses the debugging hooks in Perl and thus needs the -d
       switch, so to profile test.pl, use the command:

               perl5 -d:GraphVizProf test.pl

       Once the script is done, the statistics in smallprof.out can be sorted
       to show which lines took the most time.  The output can be sorted to
       find which lines take the longest, either with the sort command:

               sort -k 2nr,2 smallprof.out | less

       or a perl script:

               open(PROF,"smallprof.out");
               @sorted = sort {(split(/\s+/,$b))[2] <=>
                               (split(/\s+/,$a))[2]} <PROF>;
               close PROF;
               print join('',@sorted);

NOTES
       o   The "wall time" readings come from Time::HiRes and are reasonably
           useful, at least on my system.  The cpu times come from the 'times'
           built-in and the granularity is not necessarily as small as with
           the wall time.  On some systems this column may be useful.  On
           others it may not.

       o   GraphVizProf does attempt to make up for its shortcomings by
           subtracting a small amount from each timing (null time
           compensation).  This should help somewhat with the accuracy.

       o   GraphVizProf depends on the Time::HiRes package to do its timings.
           It claims to require version 1.20, but may work with earlier
           versions, depending on your platform.

OPTIONS
       GraphVizProf has 3 variables which can be used during your script to
       affect what gets profiled.

       o   If you do not wish to see lines which were never called, set the
           variable "$DB::drop_zeros = 1".  With "drop_zeros" set,
           GraphVizProf can be used for basic coverage analysis.

       o   To turn off profiling for a time, insert a "$DB::profile = 0" into
           your code (profiling may be turned back on with "$DB::profile =
           1").  All of the time between profiling being turned off and back
           on again will be lumped together and reported on the "$DB::profile
           = 0" line.  This can be used to summarize a subroutine call or a
           chunk of code.

       o   To only profile code in a certain package, set the %DB::packages
           array.  For example, to see only the code in packages "main" and
           "Test1", do this:

                   %DB::packages = ( 'main' => 1, 'Test1' => 1 );

       o   These variables can be put in a file called .smallprof in the
           current directory.  For example, a .smallprof containing

                   $DB::drop_zeros = 1;
                   $DB::profile = 0;

           will set GraphVizProf to not report lines which are never touched
           for any file profiled in that directory and will set profiling off
           initially (presumably to be turned on only for a small portion of
           code).

INSTALLATION
       Just the usual

               perl Makefile.PL
               make
               make test
               make install

       and should install fine via the CPAN module.

BUGS
       Subroutine calls are currently not under the control of %DB::packages.
       This should not be a great inconvenience in general.

       The handling of evals is bad news.  This is due to Perl's handling of
       evals under the -d flag.  For certain evals, caller() returns '(eval
       n)' for the filename and for others it doesn't.  For some of those
       which it does, the array "@{'_<filename'}" contains the code of the
       eval.  For others it doesn't.  Sometime, when I've an extra tuit or
       two, I'll figure out why and how I can compensate for this.

       Comments, advice and questions are welcome.  If you see inefficent
       stuff in this module and have a better way, please let me know.

AUTHOR
       Ted Ashton <ashted@southern.edu>

       GraphVizProf was developed from code originally posted to usenet by
       Philippe Verdret <philippe.verdret@sonovision-itep.fr>.  Special thanks
       to Geoffrey Broadwell <habusan2@sprynet.com> for his assistance on the
       Win32 platform and to Philippe for his patient assistance in testing
       and debugging.

       Copyright (c) 1997 Ted Ashton

       This module is free software; you can redistribute it or modify it
       under the Perl License, a copy of which is available at
       <http://dev.perl.org/licenses/>.

SEE ALSO
       Devel::DProf, Time::HiRes.

perl v5.38.1                      2024-01-14            Devel::GraphVizProf(3)