Calculating Perl performance

I’ve been doing some scripting in perl lately. I’ve been writing a script that generates a slew of data files and it was running really slow. I wanted to find out the bottleneck. Fortunately for me, Perl includes a nice high-level profiler. Here’s how to use it.

First run your script using the -d:dProf option:

bash-4.1$ perl -d:dProf myScript.pl

This generates a tmon.out file that contains the profile information.

Next run the dprofpp command:

bash-4.1$ perl dprofpp -u

This generates a usage report like this:

Exporter::export has -2 unstacked calls in outer
Exporter::Heavy::heavy_export has 2 unstacked calls in outer
Total Elapsed Time = 0.168504 Seconds
User Time = 0.122504 Seconds Exclusive 

Times %Time ExclSec CumulS #Calls sec/call Csec/c  Name  
13.0   0.016  0.016      3   0.0053 0.0053  vars::BEGIN  
13.0   0.016  0.016      5   0.0032 0.0031  IO::Seekable::BEGIN
13.0   0.016  0.032      7   0.0023 0.0045  IO::File::BEGIN
13.0   0.016  0.016      1   0.0159 0.0158 main::parseConfigFile
12.2   0.015  0.015      2   0.0075 0.0075  Exporter::as_heavy
12.2   0.015  0.015      3   0.0050 0.0050  File::Bsename::BEGIN
0.00   0.000  0.000      2   0.0000 0.0000 Exporter::Heavy::heavy_export
0.00       - -0.000      1        -      -  Fcntl::BEGIN
... etc

From there it’s pretty easy to figure out what’s happening. There are a lot of cool options to the dprofpp command. Check them out with the -h option.

Happy scripting!