Perl/Profiling

TLDR: Use Devel::NYTProf

How to profile Perl

Before you begin

Installing cpanm

Start by installing cpanm to take care of all your Perl packages:

brew install cpanm

Installing NYTProf

Install the best Perl profiling tool out there, the NYTProf, originally written by Adam Kaplan at the New York Times: https://www.perl.org/about/whitepapers/perl-profiling.html

cpanm Devel::NYTProf

This also installs the dependencies, of which there are multiple: https://metacpan.org/pod/Devel::NYTProf

Profiling Code using the NYTProf

Normally, we can time code using the time function, which gives a really high-level description of how long the code took to do stuff. Like, "this much user time, this much real wall time." Here's an example of output from the time command:

**************************************
Running 8 queens problem with Perl...
total 92 solutions

real	0m0.112s
user	0m0.025s
sys	0m0.008s

**************************************
Running 12 queens problem with Perl...
total 14200 solutions

real	0m11.726s
user	0m11.519s
sys	0m0.032s

We want to get a more detailed description of what's going on with the code to find bottlenecks.

Running with NYTProf

After installing it, run a Perl script with the NYTProf module turned on:

perl -d:NYTProf myscript.pl

This results in an incomprehensible nytprof.out file.

Some tools:

• nytprofcsv - export as csv file
• nytprofcfg - generates nytprof.callgraph
• nytprofhtml - generate html version

NYTProf html format

/usr/local/Cellar/perl/5.24.0_1/bin/nytprofhtml

Example:

Resources

NYTProf

Official package info (some documentation, but nothing high-level at all): https://metacpan.org/pod/Devel::NYTProf

Slide deck explaining a bit more about how to use NYTProf: www.slideshare.net/Tim.Bunce/develnytprof-200907