Re: java
Re: java
- Subject: Re: java
- From: "Craig A. Mattocks" <email@hidden>
- Date: Sun, 14 Oct 2001 23:09:55 -0400
On Sunday, 14 October 2001 20:51:21 -0500 <email@hidden> wrote:
<< It uses a VM. There may be a JIT either in place or in the works
(in seeding), but Java does not get compiled down to native code. >>
OS X now uses a version of Sun's HotSpot compiler, which compiles
portions of the Java program into native code. From their white paper
at:
http://www.sun.com/solaris/java/wp-hotspot/
Hot Spot Detection
Adaptive optimization solves the problems of JIT compilation by
taking advantage of an interesting property of most programs.
Virtually all programs spend the vast majority of their time
executing a small minority of their code. Rather than compiling
method-by-method, just in time, the Java HotSpot VM runs the program
immediately using an interpreter and analyzes the code as it runs to
detect the critical "hot spots" in the program. It then focuses the
attention of a global native-code optimizer on the hot spots. By
avoiding compilation of infrequently executed code (most of the
program), the Java HotSpot compiler can devote much more attention to
the performance-critical parts of the program, without necessarily
increasing the overall compilation time. This hot-spot monitoring is
continued dynamically as the program runs, so that it literally
adapts its performance on-the-fly to the needs of the user.
- Craig
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"This isn't right, this isn't even wrong."
- Wolfgang Pauli (1900-1958)
upon reading a young physicist's paper
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