The Dalvik team have disclosed that the recently released Android 2.0 code includes the source code for a Just In Time (JIT) compiler for Dalvik. A JIT compiler takes bytecodes and compiles them to native code for faster execution. The JIT compiler in the Android Open Source Project's release is a development snapshot and therefore is not enabled in Android 2.0, but developers can enable it for testing when compiling the "eclair" source code.

According to Bill Buzbee, a member of the Dalvik team, the JIT has "progressed significantly" since the version included in the source code. The released version had not been heavily tested when the snapshot of was taken and Buzbee advises developers who try it to expect some breakage. No details were given as to when JIT compiler development is expected to be completed.

The JIT compiler is a trace-based compiler which detects hot code and then compiles that code as needed. Minimal heap use and no need for persistent storage are features which should help the adoption of JIT into mobile devices, where the performance boost of JIT compilation has to be balanced against the cost in battery life and memory. An early test of the JIT compiler suggested an almost tripling of speed with the JIT enabled, but the tests were micro benchmarks with easily detectable and quickly compiled tests.

(djwm)