NAME

Devel::DProf - a Perl code profiler

SYNOPSIS

perl5 -d:DProf test.pl

DESCRIPTION

The Devel::DProf package is a Perl code profiler. This will collect information on the execution time of a Perl script and of the subs in that script. This information can be used to determine which subroutines are using the most time and which subroutines are being called most often. This information can also be used to create an execution graph of the script, showing subroutine relationships.

To profile a Perl script run the perl interpreter with the -d debugging switch. The profiler uses the debugging hooks. So to profile script test.pl the following command should be used:

perl5 -d:DProf test.pl

When the script terminates the profiler will dump the profile information to a file called tmon.out. A tool like dprofpp can be used to interpret the information which is in that profile. The following command will print the top 15 subroutines which used the most time:

dprofpp

To print an execution graph of the subroutines in the script use the following command:

dprofpp -T

Consult dprofpp for other options.

PROFILE FORMAT

The profile is a text file which looks like this:

#fOrTyTwO
$hz=100;
$XS_VERSION='DProf 19960205';
# All values are given in HZ
$rrun_utime=2; $rrun_stime=0; $rrun_rtime=7
PART2
+ 26 28 566822884 DynaLoader::import
- 26 28 566822884 DynaLoader::import
+ 27 28 566822885 main::bar
- 27 28 566822886 main::bar
+ 27 28 566822886 main::baz
+ 27 28 566822887 main::bar
- 27 28 566822888 main::bar
[....]

The first line is the magic number. The second line is the hertz value, or clock ticks, of the machine where the profile was collected. The third line is the name and version identifier of the tool which created the profile. The fourth line is a comment. The fifth line contains three variables holding the user time, system time, and realtime of the process while it was being profiled. The sixth line indicates the beginning of the sub entry/exit profile section.

The columns in PART2 are:

sub entry(+)/exit(-) mark
app's user time at sub entry/exit mark, in ticks
app's system time at sub entry/exit mark, in ticks
app's realtime at sub entry/exit mark, in ticks
fully-qualified sub name, when possible

AUTOLOAD

When Devel::DProf finds a call to an &AUTOLOAD subroutine it looks at the $AUTOLOAD variable to find the real name of the sub being called. See "Autoloading" in perlsub.

BUGS

XSUBs, builtin functions, and destructors cannot be measured by Devel::DProf.

Sub calls using &bar as shorthand for &bar(@_) will be broken by Devel::DProf.

Mail bug reports and feature requests to the perl5-porters mailing list at <perl5-porters@africa.nicoh.com>.

SEE ALSO

perl, dprofpp, times(2)