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
-
NVIDIA Released Driver for Upcoming NVIDIA 560 GPU for Linux
Not only has NVIDIA released the driver for its upcoming CPU series, it's the first release that defaults to using open-source GPU kernel modules.
-
OpenMandriva Lx 24.07 Released
If you’re into rolling release Linux distributions, OpenMandriva ROME has a new snapshot with a new kernel.
-
Kernel 6.10 Available for General Usage
Linus Torvalds has released the 6.10 kernel and it includes significant performance increases for Intel Core hybrid systems and more.
-
TUXEDO Computers Releases InfinityBook Pro 14 Gen9 Laptop
Sporting either AMD or Intel CPUs, the TUXEDO InfinityBook Pro 14 is an extremely compact, lightweight, sturdy powerhouse.
-
Google Extends Support for Linux Kernels Used for Android
Because the LTS Linux kernel releases are so important to Android, Google has decided to extend the support period beyond that offered by the kernel development team.
-
Linux Mint 22 Stable Delayed
If you're anxious about getting your hands on the stable release of Linux Mint 22, it looks as if you're going to have to wait a bit longer.
-
Nitrux 3.5.1 Available for Install
The latest version of the immutable, systemd-free distribution includes an updated kernel and NVIDIA driver.
-
Debian 12.6 Released with Plenty of Bug Fixes and Updates
The sixth update to Debian "Bookworm" is all about security mitigations and making adjustments for some "serious problems."
-
Canonical Offers 12-Year LTS for Open Source Docker Images
Canonical is expanding its LTS offering to reach beyond the DEB packages with a new distro-less Docker image.
-
Plasma Desktop 6.1 Released with Several Enhancements
If you're a fan of Plasma Desktop, you should be excited about this new point release.