Re: Java processors
On 7/5/2012 8:30 PM, Arne Vajh?j wrote:
On 7/5/2012 2:31 PM, Eric Sosman wrote:
On the other hand, a former colleague of mine once observed
that "Just-In-Time" is in fact a misnomer: it's a "Just-Too-Late"
compiler because it doesn't even start work until after you need
its output! Even if the JIT generates code better optimized for
the current circumstances than a pre-execution compiler could,
the JIT's code starts later. Does Achilles catch the tortoise?
It is my impression that modern JVM's especially with -server
(or equivalent) is rather aggressive about JIT compiling.
My colleague's point was that JITting the code, aggressively
or not, is pre-execution overhead: It is work spent on something
other than running your code. If you just dove in and started
interpreting you might be running more slowly, but you'd have a
head start: Achilles is the faster runner, but cannot overcome
the tortoise's lead if the race is short.
I dunno: Are JIT's nowadays smart enough to recognize code
that will (future tense) execute too few times to be worth JITting?
Static initializers without loops, say? Code in (some) catch
blocks?
--
Eric Sosman
esosman@ieee-dot-org.invalid
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