Java Magazine - May/June 2012

The difference between

OpenJDK and Oracle JDK

COMMUNITY Want to collaborate on an open source version of Java SE? Head to OpenJDK. Both individuals and companies (Apple, IBM, Oracle, Red Hat, and more) contribute code to OpenJDK. Oracle uses OpenJDK as the code base for Oracle JDK, and other organizations—particularly Linux distributions—produce builds of the Java platform based on OpenJDK sources for their distributions. Oracle JDK is a specific implementation of the JDK that is produced by Oracle. Although the code bases are very close, Oracle JDK has some minor differences. For example, Oracle JDK includes closed-source third-party components like a graphics rasterizer, third-party fonts, and additional documentation. Over time, Oracle intends to open source as much of Oracle JDK to OpenJDK as it can, except commercial features (such as Oracle JRockit Mission Control). Most of this open sourcing work involves replacing closed-source third-party components with open source alternatives or negotiating licensing agreements with third parties.

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Why use one over the other?

From a feature perspective, there is not much difference between Oracle JDK and an OpenJDK build. Oracle publishes up-to-date and fully tested JDK binaries for popular development and server platforms. For most end users and developers, this is the most convenient way to get Java. If you are an enterprise user and need long-term support, or you want the most-predictable binary distribution for an ISV application, Oracle JDK is the better choice of the two. If you want to build, create, and tweak your own JDK, perhaps to address a niche performance variable or to support a specialized platform, you will want to use OpenJDK as your code base.

—Tori Wieldt

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THE GOOD NEWS Diversity is important for open source projects.

Unfortunately, I think some people assumed the worst during the quiet period of 2009 during the acquisition, which as a bystander at the time seemed to take forever. But as soon as they could, Oracle made it clear that we were serious about OpenJDK. We wanted it to be the place to do Java SE development, first and foremost, and we wanted a lot more diversity, which means having a lot of the key Java stakeholders participate.

Java Magazine: Can you give us some concrete numbers that shed light on OpenJDK diversity?

Smith: First, let’s agree that diversity is important for open source projects. One of the lessons I learned at Eclipse is that diversity is an important metric for the quality and longevity of projects. Optimally, you want to have a diverse mix of types and sizes of organizations and some key individuals participating in an open source project. It’s also a plus to have diversity based on geography, experience, and other factors.

For OpenJDK, the initial code base and contribution came from Sun and then Oracle so we started from a position of low diversity,

which is typical of many open source communities that start with a large initial contribution. But we want to keep pushing in the direction of more diversity. We can debate how fast and how far we move toward this, but pretty much everyone in the community agrees that we seek diversity.

The good news, based upon the census taken when the bylaws were approved in mid- 2011, is that we have about 350 developers in the OpenJDK community, and about 80 of those are not employed by Oracle. This is a good start. We can also look at diversity in terms of e-mail traffic—about 40 percent of the e-mail traffic, according to MarkMail, is from non-Oracle employees.