DevNation Tuesday is Tech Fun Day

I decided to theme each day of my DevNation conference attendance so that I could achieve some sense of a goal and also help me select which tracks to attend. For Tuesday, I went with the “go to something you love, or something you know nothing about” theme.

Here is where I will be:
10:40-11:40 DevAssistant: What’s in it for you? with Bohuslav Kabrda
If I achieve nothing else in the next two years of my career with Team Inception, I want to be aware of the current technologies that make developer’s lives easier. Since we have similar issues here in Red Hat IT, I’d love to see what DevAssistant can potentially do for the developers within the department… possibly see if it can be extended for other purposes?

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How to add a new package to RHSCL perl516 for RHEL

The Red Hat Software Collection (RHSCL) perl516 contains only a part of the packages which are packaged in RHEL or Fedora. It is not hard to add a new package to RHSCL. The following steps show how to convert a conventional spec file into a Software Collection spec file. The SCL spec file can then be used in both the conventional package and the Software Collection. We will use perl-Pod-Perldoc is used for an example.

Before you start, spec2scl rpm has to be installed.

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Red Hat has been working on new and innovative ways to deliver alternate versions of system software for some time. In 2012, we released the 1.0 of the Red Hat Developer Toolset (DTS) which was the first product to use Software Collections. About six months ago, Red Hat took the wraps off of Red Hat Software Collections 1.0 for Red Hat Enterprise Linux (RHEL). Now we’re pleased to announce, a project for creating, hosting, and delivering community created Software Collections for RHEL, CentOS, and Fedora.

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Apache with various PHP versions, using SCL

RHSCL 1.1 Beta is available and provides Apache httpd 2.4, PHP 5.4 and PHP 5.5.

The most common configuration for Apache and PHP uses mod_php, but this only allows a single PHP version. Apache httpd 2.4 introduces mod_proxy_fgci which can simply redirect requests to a php-fpm backend.

This article shows a simple way to use a single Apache server and simultaneously run 3 versions of PHP (5.3, 5.4 and 5.5). The same site will be served through 3 sub-URL.

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Which tasks are periodically taking processor time?

When running a latency-sensitive application one might notice that on a regular basis (for example every 5 minutes) there is a delay. The SystemTap periodic.stp script can provide some possible causes of that regular delay. The SystemTap periodic.stp script generates a list of the number of times that various scheduled functions run and the time between each scheduled execution. In the case of delay every five minutes one would run the periodic script for tens of minutes and then look through the output list for a function that has a period of approximately 300,000,00 microseconds (5 minutes*60 seconds*1,000,000 microseconds/second).

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Repost – The Application Apartment Complex: Red Hat Enterprise Linux & Linux Containers

With April showers, comes talk about containers.  (Well, not exactly, but there’s a lot of container discussion going on these days.)  Bhavna has produced this excellent article to summarize Red Hat’s efforts on them.  Here’s an excerpt:

“Let’s dive into world of containers. Red Hat customers often desire for their applications to run in a secure environment and have been seeking, whether they actually know it or not, a fully supported light weight application isolation solution.  At the other end of the spectrum, ISVs want to develop software applications that are easy to deploy, update, and scale.  They may also want to more precisely control certain runtime elements so as to reduce the risk of application failure, and desire a separation of host OS and runtime images.  And let’s not forget that developers stand to benefit from a world where they can build and package their applications into a small, portable runtime image; just think of the possibilities!

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Which task is getting all the CPU processor cycles?

If an important task is processor limited, one would like to make sure that the task is getting as much processor time as possible and other tasks are not delaying the execution of the important task. The SystemTap example script, cycle_thief.stp, lists what interrupts and other tasks run on the same processor as the important task. The cycle_thief.stp script provides the following pieces of information: