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

       •   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.

       •   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.

       •   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.

       •   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.

       •   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.

       •   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 );

       •   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.