Azul's Zulu OpenJDK Now Available on Docker

Java runtime maker Azul Systems announced today that its build of the OpenJDK known as Zulu is now freely available on the open-source Docker container platform. The company also announced that Zulu 8.0, the current version released in April, is now compliant with the Java SE 7 and SE 6 standards available on Docker in the same format.

The open source Docker project (, which has created a platform for building, managing, and deploying apps as lightweight, portable, self-sufficient software containers, has been catching fire in the enterprise recently. To date, the project has attracted more than 600 contributors from around the world, according to the project website, and generated more than a million downloads. More than 14,000 "dockerized" apps are currently listed on the Docker public Registry, and about 7,000 projects now on GitHub have "Docker" in their titles.

"The transition we've seen in our customer base and with prospects has really been eye-opening," Azul CEO Scott Sellers told ADTmag. "We're hearing about companies actively ripping out their traditional virtualization solutions for Docker. Kind of amazing, given the traditionally conservative nature of IT."

Containerization differs from hypervisor-based virtualization in some significant ways. Containers are lightweight, in that they carry no operating system; apps within a container start up immediately, almost as fast as apps running on an OS; they are fully isolated; they consume fewer physical resources; and there's little of the performance overhead associated with virtualization -- no "virtualization tax."

"Docker and containerization are taking the enterprise IT world by storm as a better way to package, deploy and move applications," 451 Research analyst Jay Lyman said in a statement, "but there is still a lot of work required to make Docker enterprise-ready in terms of security, scale, and management. Support for Java SE 8 on Docker is a step in the right direction, giving enterprise Docker users some of the security, stability and compliance assurances they expect."

But Sellers credits the acceptance and widespread use of virtualization technologies in the enterprise over the past decade with paving the road for containerization. "This is not new technology," he said, "but it's what has happened in the past ten years with virtualization that has created the here-and-now opportunity for Docker and this very fast-moving trend."

Zulu 8.0 runs on Windows, Windows Server, Mac OS X, and multiple Linux distributions (Red Hat Enterprise Linux, SUSE Linux Enterprise Server, CentOS, Ubuntu). It's actually the product of a partnership between Azul and the Microsoft Open Technologies group (MS Open Tech). The two organizations joined forces in 2013 to create a version of OpenJDK specifically for Windows Azure. In September of that year, the two companies unveiled Zulu for Windows Server and Windows Azure. Earlier this year, the company launched a version of Zulu for both Java 6 and Java 7 running on Linux and Windows.

The Sunnyvale, Calif.-based Azul Systems' flagship product, Zing, is a Java Virtual Machine (JVM) based on Oracle's HotSpot JVM, a core component of Java SE. It's a "no-pause" JVM designed to eliminate Garbage Collection (GC) pauses, a long-standing challenge for Java developers. This pauselessness, which Azul calls "generational pauseless garbage collection" (GPGC), enables Java app instances to scale dynamically and reliably. Azul has long targeted GC, which Sellers has called the Achilles heel of Java.

About the Author

John K. Waters is the editor in chief of a number of sites, with a focus on high-end development, AI and future tech. He's been writing about cutting-edge technologies and culture of Silicon Valley for more than two decades, and he's written more than a dozen books. He also co-scripted the documentary film Silicon Valley: A 100 Year Renaissance, which aired on PBS.  He can be reached at [email protected].