Oracle set to merge Java virtual machines

Oracle's plan to merge the Sun HotSpot Java Virtual Machine with the JRockit JVM is still evolving, but a single JVM based on both technologies is expected in 18 months to two years, an Oracle official has revealed

Asked about the company's plans to mix the JVMs during an Oracle Webcast last week, Mark Reinhold, Oracle's principal engineer and a holdover from Sun, said the company would continue to develop both platforms in the short term. A JVM enables running of Java programs and provides Java's heralded hardware and operating system independence.

Last month Oracle expressed intentions to integrate the two JVMs during a Sun-Oracle roadmap session. Oracle had acquired JRockit when it bought BEA Systems two years ago.

"It's not an easy problem taking the best of each, figuring out what the long-term convergence plan is," said Reinhold. "We're not going to just stop doing one of them. Customers have things in production on both, taking advantage of specific features in both. We're not going to cause an earthquake and make systems fall over," he said.

"At some point in time, I expect there will be one VM." He gave an estimated timeframe of one-and-a-half to two years for this to happen.

The two JVMs are distinguishable from each other, said Reinhold. "There's stuff in JRockit that, frankly, we've been jealous of for some years. The mission control stuff is very sweet."

HotSpot, meanwhile, has an advantage in pushing of performance, he said. "Our sense with the HotSpot code, especially the server compiler, is there is a lot more head room there. It is a lot more sophisticated [as a] system."

Reinhold speculated the merged VM could have the JRockit garbage collector and serviceability, the HotSpot runtime compiler and a mixed runtime system. "It's been fascinating to learn more about JRockit over the last couple of months. It really is a world-class VM."

The plan to mix the two JVMs for the short and long terms has been "the subject of many recent meetings," he said.

As well, he touted the planned Java Development Kit 7 that serves as the next version of the standard edition of Java. He cited its modularity and multilingual capabilities, as well as intentions to make it a more productive platform and have it scale down to small devices.

Java platform developers intend to incorporate efforts from Project Coin, which pertains to small language changes, into JDK 7, Reinhold noted.