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1 | use 5.006_001; |
2 | ||
3 | =head1 NAME | |
4 | ||
5 | Devel::DProf - a Perl code profiler | |
6 | ||
7 | =head1 SYNOPSIS | |
8 | ||
9 | perl -d:DProf test.pl | |
10 | ||
11 | =head1 DESCRIPTION | |
12 | ||
13 | The Devel::DProf package is a Perl code profiler. This will collect | |
14 | information on the execution time of a Perl script and of the subs in that | |
15 | script. This information can be used to determine which subroutines are | |
16 | using the most time and which subroutines are being called most often. This | |
17 | information can also be used to create an execution graph of the script, | |
18 | showing subroutine relationships. | |
19 | ||
20 | To profile a Perl script run the perl interpreter with the B<-d> debugging | |
21 | switch. The profiler uses the debugging hooks. So to profile script | |
22 | F<test.pl> the following command should be used: | |
23 | ||
24 | perl -d:DProf test.pl | |
25 | ||
26 | When the script terminates (or when the output buffer is filled) the | |
27 | profiler will dump the profile information to a file called | |
28 | F<tmon.out>. A tool like I<dprofpp> can be used to interpret the | |
29 | information which is in that profile. The following command will | |
30 | print the top 15 subroutines which used the most time: | |
31 | ||
32 | dprofpp | |
33 | ||
34 | To print an execution graph of the subroutines in the script use the | |
35 | following command: | |
36 | ||
37 | dprofpp -T | |
38 | ||
39 | Consult L<dprofpp> for other options. | |
40 | ||
41 | =head1 PROFILE FORMAT | |
42 | ||
43 | The old profile is a text file which looks like this: | |
44 | ||
45 | #fOrTyTwO | |
46 | $hz=100; | |
47 | $XS_VERSION='DProf 19970606'; | |
48 | # All values are given in HZ | |
49 | $rrun_utime=2; $rrun_stime=0; $rrun_rtime=7 | |
50 | PART2 | |
51 | + 26 28 566822884 DynaLoader::import | |
52 | - 26 28 566822884 DynaLoader::import | |
53 | + 27 28 566822885 main::bar | |
54 | - 27 28 566822886 main::bar | |
55 | + 27 28 566822886 main::baz | |
56 | + 27 28 566822887 main::bar | |
57 | - 27 28 566822888 main::bar | |
58 | [....] | |
59 | ||
60 | The first line is the magic number. The second line is the hertz value, or | |
61 | clock ticks, of the machine where the profile was collected. The third line | |
62 | is the name and version identifier of the tool which created the profile. | |
63 | The fourth line is a comment. The fifth line contains three variables | |
64 | holding the user time, system time, and realtime of the process while it was | |
65 | being profiled. The sixth line indicates the beginning of the sub | |
66 | entry/exit profile section. | |
67 | ||
68 | The columns in B<PART2> are: | |
69 | ||
70 | sub entry(+)/exit(-) mark | |
71 | app's user time at sub entry/exit mark, in ticks | |
72 | app's system time at sub entry/exit mark, in ticks | |
73 | app's realtime at sub entry/exit mark, in ticks | |
74 | fully-qualified sub name, when possible | |
75 | ||
76 | With newer perls another format is used, which may look like this: | |
77 | ||
78 | #fOrTyTwO | |
79 | $hz=10000; | |
80 | $XS_VERSION='DProf 19971213'; | |
81 | # All values are given in HZ | |
82 | $over_utime=5917; $over_stime=0; $over_rtime=5917; | |
83 | $over_tests=10000; | |
84 | $rrun_utime=1284; $rrun_stime=0; $rrun_rtime=1284; | |
85 | $total_marks=6; | |
86 | ||
87 | PART2 | |
88 | @ 406 0 406 | |
89 | & 2 main bar | |
90 | + 2 | |
91 | @ 456 0 456 | |
92 | - 2 | |
93 | @ 1 0 1 | |
94 | & 3 main baz | |
95 | + 3 | |
96 | @ 141 0 141 | |
97 | + 2 | |
98 | @ 141 0 141 | |
99 | - 2 | |
100 | @ 1 0 1 | |
101 | & 4 main foo | |
102 | + 4 | |
103 | @ 142 0 142 | |
104 | + & Devel::DProf::write | |
105 | @ 5 0 5 | |
106 | - & Devel::DProf::write | |
107 | ||
108 | (with high value of $ENV{PERL_DPROF_TICKS}). | |
109 | ||
110 | New C<$over_*> values show the measured overhead of making $over_tests | |
111 | calls to the profiler These values are used by the profiler to | |
112 | subtract the overhead from the runtimes. | |
113 | ||
114 | The lines starting with C<@> mark time passed from the previous C<@> | |
115 | line. The lines starting with C<&> introduce new subroutine I<id> and | |
116 | show the package and the subroutine name of this id. Lines starting | |
117 | with C<+>, C<-> and C<*> mark entering and exit of subroutines by | |
118 | I<id>s, and C<goto &subr>. | |
119 | ||
120 | The I<old-style> C<+>- and C<->-lines are used to mark the overhead | |
121 | related to writing to profiler-output file. | |
122 | ||
123 | =head1 AUTOLOAD | |
124 | ||
125 | When Devel::DProf finds a call to an C<&AUTOLOAD> subroutine it looks at the | |
126 | C<$AUTOLOAD> variable to find the real name of the sub being called. See | |
127 | L<perlsub/"Autoloading">. | |
128 | ||
129 | =head1 ENVIRONMENT | |
130 | ||
131 | C<PERL_DPROF_BUFFER> sets size of output buffer in words. Defaults to 2**14. | |
132 | ||
133 | C<PERL_DPROF_TICKS> sets number of ticks per second on some systems where | |
134 | a replacement for times() is used. Defaults to the value of C<HZ> macro. | |
135 | ||
136 | C<PERL_DPROF_OUT_FILE_NAME> sets the name of the output file. If not set, | |
137 | defaults to tmon.out. | |
138 | ||
139 | =head1 BUGS | |
140 | ||
141 | Builtin functions cannot be measured by Devel::DProf. | |
142 | ||
143 | With a newer Perl DProf relies on the fact that the numeric slot of | |
144 | $DB::sub contains an address of a subroutine. Excessive manipulation | |
145 | of this variable may overwrite this slot, as in | |
146 | ||
147 | $DB::sub = 'current_sub'; | |
148 | ... | |
149 | $addr = $DB::sub + 0; | |
150 | ||
151 | will set this numeric slot to numeric value of the string | |
152 | C<current_sub>, i.e., to C<0>. This will cause a segfault on the exit | |
153 | from this subroutine. Note that the first assignment above does not | |
154 | change the numeric slot (it will I<mark> it as invalid, but will not | |
155 | write over it). | |
156 | ||
157 | Another problem is that if a subroutine exits using goto(LABEL), | |
158 | last(LABEL) or next(LABEL) then perl may crash or Devel::DProf will die | |
159 | with the error: | |
160 | ||
161 | panic: Devel::DProf inconsistent subroutine return | |
162 | ||
163 | For example, this code will break under Devel::DProf: | |
164 | ||
165 | sub foo { | |
166 | last FOO; | |
167 | } | |
168 | FOO: { | |
169 | foo(); | |
170 | } | |
171 | ||
172 | A pattern like this is used by Test::More's skip() function, for | |
173 | example. See L<perldiag> for more details. | |
174 | ||
175 | Mail bug reports and feature requests to the perl5-porters mailing list at | |
176 | F<E<lt>perl5-porters@perl.orgE<gt>>. | |
177 | ||
178 | =head1 SEE ALSO | |
179 | ||
180 | L<perl>, L<dprofpp>, times(2) | |
181 | ||
182 | =cut | |
183 | ||
184 | # This sub is needed for calibration. | |
185 | package Devel::DProf; | |
186 | ||
187 | sub NONESUCH_noxs { | |
188 | return $Devel::DProf::VERSION; | |
189 | } | |
190 | ||
191 | package DB; | |
192 | ||
193 | # | |
194 | # As of perl5.003_20, &DB::sub stub is not needed (some versions | |
195 | # even had problems if stub was redefined with XS version). | |
196 | # | |
197 | ||
198 | # disable DB single-stepping | |
199 | BEGIN { $single = 0; } | |
200 | ||
201 | # This sub is needed during startup. | |
202 | sub DB { | |
203 | # print "nonXS DBDB\n"; | |
204 | } | |
205 | ||
206 | use XSLoader (); | |
207 | ||
208 | $Devel::DProf::VERSION = '20050603.00'; # this version not authorized by | |
209 | # Dean Roehrich. See "Changes" file. | |
210 | ||
211 | XSLoader::load 'Devel::DProf', $Devel::DProf::VERSION; | |
212 | ||
213 | 1; |