Profilers identify bottlenecks in Perl programs
Not Without Side Effects
Just like any other profiler, Devel::NYTProf also involves some overhead that can completely falsify the measured results in some cases. The profiler's activities are particularly invasive if a program is not waiting for external events, such as network traffic or disk access, which are magnitudes of scale slower.
For a program running at full CPU speed, the run time can be 10 times longer if you enable the profiler.
Figure 7 shows the effect the NYT profiler has on the short l4ptest test program (Listing 4). The program configures Log4perl for the $INFO logging priority and then issues $DEBUG messages, which should be suppressed because of their lower priority. Log4perl has optimized this case; after all, a disabled logging system shouldn't have any measurable effect.
Listing 4
l4ptest
#!/usr/local/bin/perl -w use strict; use Log::Log4perl qw(:easy); Log::Log4perl->easy_init($INFO); for(1..100_000) { DEBUG "waah!"; }
The script running without the profiler achieves around 100,000 calls in about 100msec; the script run time is about 10 times longer with NYTProf enabled.
This by no means detracts from the quality of the profiler, but it is important to take this into consideration when measuring script run time and interpreting the results.
The module also is quite at home in the Apache server's mod_perl. Adding PerlModule Devel::NYTProf::Apache to the configuration loads the module and tells it to append profile data to the /tmp/nytprof.$$.out file for incoming requests, where $$ represents the PID for the Apache process handling the request.
Calling nytprofhtml again creates a collection of web pages for in-depth analysis of the web application's performance that could very well point you to critical code sections that need improvement.
Infos
- Listings for this article: http://www.linux-magazine.com/resources/article_code
- Amazon Web Services (developer token application): http://amazon.com/soap
- Devel::NYTProf: http://search.cpan.org/dist/Devel-NYTProf/
- Tim Bunce blog "NYTProf v2 – the background story," http://blog.timbunce.org/2008/07/16/nytprof-v2-the-background-story/
- Tim Bunce at OSCON 2008: http://en.oreilly.com/oscon2008/public/schedule/speaker/6816
« Previous 1 2 3
Buy this article as PDF
(incl. VAT)
Buy Linux Magazine
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Support Our Work
Linux Magazine content is made possible with support from readers like you. Please consider contributing when you’ve found an article to be beneficial.
News
-
Fedora Asahi 40 Remix Available for Macs with Apple Silicon
If you've been anticipating KDE's Plasma 6 for your Apple Silicon-powered Mac, then you're in luck.
-
Red Hat Adds New Deployment Option for Enterprise Linux Platforms
Red Hat has re-imagined enterprise Linux for an AI future with Image Mode.
-
OSJH and LPI Release 2024 Open Source Pros Job Survey Results
See what open source professionals look for in a new role.
-
Proton 9.0-1 Released to Improve Gaming with Steam
The latest release of Proton 9 adds several improvements and fixes an issue that has been problematic for Linux users.
-
So Long Neofetch and Thanks for the Info
Today is a day that every Linux user who enjoys bragging about their system(s) will mourn, as Neofetch has come to an end.
-
Ubuntu 24.04 Comes with a “Flaw"
If you're thinking you might want to upgrade from your current Ubuntu release to the latest, there's something you might want to consider before doing so.
-
Canonical Releases Ubuntu 24.04
After a brief pause because of the XZ vulnerability, Ubuntu 24.04 is now available for install.
-
Linux Servers Targeted by Akira Ransomware
A group of bad actors who have already extorted $42 million have their sights set on the Linux platform.
-
TUXEDO Computers Unveils Linux Laptop Featuring AMD Ryzen CPU
This latest release is the first laptop to include the new CPU from Ryzen and Linux preinstalled.
-
XZ Gets the All-Clear
The back door xz vulnerability has been officially reverted for Fedora 40 and versions 38 and 39 were never affected.