Excelsior Jet, a JVM with Ahead-Of-Time compiler has been updated to verision 4.5. Jet precompiles JVM byte code to native X86 instructions. Precompilation removes the overhead of bytecode interpretation. Compiled Java code also does not contain the same information as bytecode which prevents easy decompilation. According to Excelsior's website Jet compiled applications are also often significantly smaller in size.
New features included in version 4.5:
- Support for Java SE 5.0 Update 6 (1.5.0_06)
- Application Download Size Reductions
- Rebranding Support for the Excelsior Installer
- Excelsior Installer for Linux Support
- JIT Compilation Now 3-5x Faster
Community comments
Isn't JIT faster than static compilers?
by Emmanuel Bernard,
Re: Isn't JIT faster than static compilers?
by Dmitry Leskov,
Isn't JIT faster than static compilers?
by Emmanuel Bernard,
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I can be wrong, but I though JIT compiler had more informations and hence could produce better native code that static compilers.
Feel free to debunk :-)
Re: Isn't JIT faster than static compilers?
by Dmitry Leskov,
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As usual, making the last 20% of optimizations takes 80% of resources. :) So the key word here is "could". In reality, this is only possible for long-running applications on systems with plenty of RAM and CPU time available to the JIT compiler. And, you know, applications need CPU and RAM too...
So I would say static compilers have an advantage on the desktop, where your app must load fast and work at full speed right upon startup, and especially in embedded systems, where dynamic (JIT) compilers may have no resources for doing any sophisticated optimizations.
It is also perfectly possible to collect the application execution profile during a load test and feed that profile to the static compiler on next compilation. In fact, we are working on this right now, so stay tuned.
Finally, compilation to native code has other advantages, such as protection from Java decompilers. We have customers whose pre-compiled applications do not work any faster than if run on HotSpot, but they need to protect their IP, so they bought Excelsior JET.
Dmitry Leskov
Excelsior LLC