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Devel::GraphVizProf(3)User Contributed Perl DocumentatioDevel::GraphVizProf(3)

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

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

       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

	       <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, use the command:

	       perl5 -d:GraphVizProf

       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:

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

       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.

       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

       Just the	usual

	       perl Makefile.PL
	       make test
	       make install

       and should install fine via the CPAN module.

       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.

       Ted Ashton <>

       GraphVizProf was	developed from code originally posted to usenet	by
       Philippe	Verdret	<>.	Special	thanks
       to Geoffrey Broadwell <> 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

       Devel::DProf, Time::HiRes.

perl v5.32.1			  2016-12-27		Devel::GraphVizProf(3)


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