1Devel::GraphVizProf(3)User Contributed Perl DocumentationDevel::GraphVizProf(3)
2
6 Devel::GraphVizProf - per-line Perl profiler (with graph output)
7
9 perl -d:GraphVizProf test.pl > test.dot
10 dot -Tpng test.dot > test.png
11
13 NOTE: This module is a hack of Devel::SmallProf by Ted Ashton. It has
14 been modified by Leon Brocard to produce output for GraphViz, but
15 otherwise the only thing I have done is change the name. I hope to get
16 my patches put into the main Devel::SmallProf code eventually, or
17 alternatively read the output of Devel::SmallProf. Anyway, the normal
18 documentation, which you can probably ignore, follows.
19 The Devel::GraphVizProf profiler is focused on the time taken for a
21 program run on a line-by-line basis. It is intended to be as "small"
22 in terms of impact on the speed and memory usage of the profiled
23 program as possible and also in terms of being simple to use. Those
24 statistics are placed in the file smallprof.out in the following
25 format:
26 <num> <time> <ctime> <line>:<text>
28 where <num> is the number of times that the line was executed, <time>
30 is the amount of "wall time" (time according the the clock on the wall
31 vs. cpu time) spent executing it, <ctime> is the amount of cpu time
32 expended on it and <line> and <text> are the line number and the actual
33 text of the executed line (read from the file).
34 The package uses the debugging hooks in Perl and thus needs the -d
36 switch, so to profile test.pl, use the command:
37 perl5 -d:GraphVizProf test.pl
39 Once the script is done, the statistics in smallprof.out can be sorted
41 to show which lines took the most time. The output can be sorted to
42 find which lines take the longest, either with the sort command:
43 sort -k 2nr,2 smallprof.out | less
45 or a perl script:
47 open(PROF,"smallprof.out");
49 @sorted = sort {(split(/\s+/,$b))[2] <=>
50 (split(/\s+/,$a))[2]} <PROF>;
51 close PROF;
52 print join('',@sorted);
53
55 • The "wall time" readings come from Time::HiRes and are reasonably
56 useful, at least on my system. The cpu times come from the 'times'
57 built-in and the granularity is not necessarily as small as with
58 the wall time. On some systems this column may be useful. On
59 others it may not.
60 • GraphVizProf does attempt to make up for its shortcomings by
62 subtracting a small amount from each timing (null time
63 compensation). This should help somewhat with the accuracy.
64 • GraphVizProf depends on the Time::HiRes package to do its timings.
66 It claims to require version 1.20, but may work with earlier
67 versions, depending on your platform.
68
70 GraphVizProf has 3 variables which can be used during your script to
71 affect what gets profiled.
72 • If you do not wish to see lines which were never called, set the
74 variable "$DB::drop_zeros = 1". With "drop_zeros" set,
75 GraphVizProf can be used for basic coverage analysis.
76 • To turn off profiling for a time, insert a "$DB::profile = 0" into
78 your code (profiling may be turned back on with "$DB::profile =
79 1"). All of the time between profiling being turned off and back
80 on again will be lumped together and reported on the "$DB::profile
81 = 0" line. This can be used to summarize a subroutine call or a
82 chunk of code.
83 • To only profile code in a certain package, set the %DB::packages
85 array. For example, to see only the code in packages "main" and
86 "Test1", do this:
87 %DB::packages = ( 'main' => 1, 'Test1' => 1 );
89 • These variables can be put in a file called .smallprof in the
91 current directory. For example, a .smallprof containing
92 $DB::drop_zeros = 1;
94 $DB::profile = 0;
95 will set GraphVizProf to not report lines which are never touched
97 for any file profiled in that directory and will set profiling off
98 initially (presumably to be turned on only for a small portion of
99 code).
100
102 Just the usual
103 perl Makefile.PL
105 make
106 make test
107 make install
108 and should install fine via the CPAN module.
110
112 Subroutine calls are currently not under the control of %DB::packages.
113 This should not be a great inconvenience in general.
114 The handling of evals is bad news. This is due to Perl's handling of
116 evals under the -d flag. For certain evals, caller() returns '(eval
117 n)' for the filename and for others it doesn't. For some of those
118 which it does, the array "@{'_<filename'}" contains the code of the
119 eval. For others it doesn't. Sometime, when I've an extra tuit or
120 two, I'll figure out why and how I can compensate for this.
121 Comments, advice and questions are welcome. If you see inefficent
123 stuff in this module and have a better way, please let me know.
124
126 Ted Ashton <ashted@southern.edu>
127 GraphVizProf was developed from code originally posted to usenet by
129 Philippe Verdret <philippe.verdret@sonovision-itep.fr>. Special thanks
130 to Geoffrey Broadwell <habusan2@sprynet.com> for his assistance on the
131 Win32 platform and to Philippe for his patient assistance in testing
132 and debugging.
133 Copyright (c) 1997 Ted Ashton
135 This module is free software; you can redistribute it or modify it
137 under the Perl License, a copy of which is available at
138 <http://dev.perl.org/licenses/>.
139
141 Devel::DProf, Time::HiRes.
142perl v5.34.0 2021-07-22 Devel::GraphVizProf(3)