Linux

WebSockets are a rising technology that solves one of the great needs of web development - full duplex communication between a browser (or a different client) and a server. Let's imagine a simple scenario - live web chat. In the past, you'd probably use AJAX and polling to make new posts appear in realtime. The downside is that implementing all that is not entirely easy and it tends to put a lot of strain on the server. This article will...

As I stare at this blank screen to start writing my first blog entry I have that same feeling that so many developers have when starting with an unfamiliar programming language or application. The developers in our group realize that it is not easy starting from nothing and we strive to make it easier to productively use SystemTap to investigate performance problems. A starting point for anyone's first use of SystemTap is the SystemTap Beginners Guide on the Red Hat...

Unfortunately, not every application is packaged for every distribution. What do you do when you can't find it packaged for Red Hat Enterprise Linux? If you are like most people, you give up or attempt to install it from source. What happens when installing from source goes badly? If you are like most people, you definitely give up. How do you keep up with application improvements or, perhaps more importantly, security fixes? If you are like most people, you periodically...

Recently, I needed to get Django installed with Python 2.7 on Red Hat Enterprise Linux 6. As this is not a directly supported activity, I wanted to document how I went about it. As you might imagine, the generally expected method for install would be to grab the Python 2.7 source tree and then build it. Obviously, that can be a lot of work; is not particularly repeatable; and, potentially, exposes you to more security flaws. As a result, I...

This technical article covers a subtlety in C++ array allocation and how we changed the GNU C++ compiler to deal with it properly. When a programmer writes T *p = new T[3]; the C++ compiler allocates room for at least three copies of objects of type T on the heap. These objects require 3 * sizeof(T) bytes. For this example, assume sizeof(T) is 12, then it is straightforward to allocate 36 bytes (for example, using malloc). But what happens if...

While Red Hat Enterprise Linux is known for its stability and flexibility, you might not think of it first when looking for the latest version of your web application framework. If you're a developer working with Ruby and Ruby on Rails, you probably want to take advantage of their new features. Sure, you can use RVM, but sometimes you just want to get supported system packages. Software Collections (often abbreviated as SCL) allows you to run more recent versions of...

Did you ever wish you had newer versions of the software on your Red Hat Enterprise Linux machines? You are probably not alone. Providing new versions of software in rpm is hard, because rpm supports only one version installed on your computer at a time. Multiple versions on one machine can conflict with each other or create unpredictable behaviour in applications that you might not have considered dependencies. Last year, we developed Software Collections to allow you to install newer...