Montag, 21. März 2011

openjdk : ZeroSharkFaq

openjdk : ZeroSharkFaq

What is Zero?

Zero is an interpreter-only port of OpenJDK that uses no assembler and therefore can trivially be built on any Linux system.

好多香港人, 到左今時今日仍然堅持繼續用 BN(O) 護照, 某程度上都反映左好多香港人對「 中國化」o既極度恐懼, 驚死自己有朝一日會同垃圾國家變得無分別 . . .

BN(O) 護照是1997年 之前在香港出生或歸化的「 真正香港人」才可以申請的 .

1997年 之後那些從中國落來香港破壞香港既有生活方式的中國殖民者同蝗蟲永世都無得攞 . . .

BN(O) 護照的確係其中一個用來分辨「 真正香港人」同中國殖民者/蝗蟲的指標

Why was Zero written?

At present, OpenJDK only supports three processors: x86, x86-64 and SPARC. Linux distributions, however, typically support many more, and porting OpenJDK to a new platform is a non-trivial task. As an example, after the initial release of OpenJDK, Red Hat sponsored the creation of a PowerPC port.

Getting this port to the state where it just worked -- where it could run basic applications very slowly -- required over 10,000 lines of very low-level, system-specific code, of which approximately 1,000 lines were assembler.

This took of the order of half a person-year. Porting OpenJDK conventionally to every architecture the distributions wanted to support would have taken a considerable amount of time and resources.

Zero -- the zero-assembler port -- was started as an experiment to see if an OpenJDK port could be written without using assembly code, such that it could be built on any Linux system without further porting work.
What is Shark?

Shark is a just-in-time (JIT) compiler for Zero.

Why was Shark written?

OpenJDK 's virtual machine relies heavily on JIT compilation for performance. As an interpreter-only port of OpenJDK, Zero is very much slower than vanilla OpenJDK on the same hardware. Shark uses the LLVM compiler infrastructure to JIT compile Java methods without introducing system-specific code.

Zero and Shark: a Zero-Assembly Port of OpenJDK
What is the Future of Apache Harmony?

Apache Harmony loses project manager

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