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Re: Java processors

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From Lew <lewbloch@gmail.com>
Newsgroups comp.lang.java.programmer
Subject Re: Java processors
Date Fri, 6 Jul 2012 14:17:40 -0700 (PDT)
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Gene Wirchenko wrote:
> Roedy Green wrote:
>>Eric Sosman wrote, quoted or indirectly quoted someone who said :
>>> If you just dove in and started
>>> interpreting you might be running more slowly, but you'd have a
>>> head start
>>
>> That is just what JITs do. It is only after a while they have gathered
>> some stats to they decide which classes to turn to machine code. The
>> astounding thing is they stop the interpreter in mid flight executing
>> a method, and replace it with machine code and restart it. That to me
>> is far more impressive than walking on water.

They don't do that exactly. There's no restart.

<http://www.oracle.com/technetwork/java/hotspotfaq-138619.html#compiler_warmup>
 
>      Do you have a cite [sic] for that?  Restarting a method could be messy.

This was in the links I provided upthread.

> Imagine if files are opened, other objects created, etc.
> 
>      I suspect that it might be as prosaic as a method execution times
> counter reaching a threshold value triggering the conversion.

Also cited upthread. I don't know that it's method-by-method; I 
think HotSpot optimizes at finer granularity than that. The cited 
reference refers to optimizing "loops".

But it's far from prosaic. The HotSpot compiler (not to be confused with 
other JIT compilers) can switch to native-compiled code mid-execution 
while the interpreted code is running. Given that the compiler is 
aware of run-time circumstances, I don't know that it would need to 
have trouble with file handles and the sorts of things you mention.

-- 
Lew

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Thread

Java processors bob smith <bob@coolfone.comze.com> - 2012-07-05 08:01 -0700
  Re: Java processors Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-07-05 11:28 -0400
    Re: Java processors BGB <cr88192@hotmail.com> - 2012-07-05 13:00 -0500
      Re: Java processors Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-07-05 14:31 -0400
        Re: Java processors BGB <cr88192@hotmail.com> - 2012-07-05 16:42 -0500
        Re: Java processors Arne Vajhøj <arne@vajhoej.dk> - 2012-07-05 20:30 -0400
          Re: Java processors BGB <cr88192@hotmail.com> - 2012-07-05 21:12 -0500
          Re: Java processors Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-07-06 00:13 -0400
            Re: Java processors Roedy Green <see_website@mindprod.com.invalid> - 2012-07-06 13:26 -0700
              Re: Java processors Gene Wirchenko <genew@ocis.net> - 2012-07-06 13:50 -0700
                Re: Java processors Lew <lewbloch@gmail.com> - 2012-07-06 14:17 -0700
                Re: Java processors Roedy Green <see_website@mindprod.com.invalid> - 2012-07-06 19:07 -0700
                Re: Java processors BGB <cr88192@hotmail.com> - 2012-07-07 09:34 -0500
                Re: Java processors Roedy Green <see_website@mindprod.com.invalid> - 2012-07-07 21:01 -0700
                Re: Java processors BGB <cr88192@hotmail.com> - 2012-07-08 00:28 -0500
                Re: Java processors Lew <noone@lewscanon.com> - 2012-07-07 23:00 -0700
                Re: Java processors BGB <cr88192@hotmail.com> - 2012-07-08 10:20 -0500
                Re: Java processors Lew <noone@lewscanon.com> - 2012-07-08 09:16 -0700
                Re: Java processors Martin Gregorie <martin@address-in-sig.invalid> - 2012-07-08 17:46 +0000
                Re: Java processors Lew <noone@lewscanon.com> - 2012-07-08 11:52 -0700
                Re: Java processors Martin Gregorie <martin@address-in-sig.invalid> - 2012-07-08 21:41 +0000
                Re: Java processors Lew <noone@lewscanon.com> - 2012-07-08 17:56 -0700
                Re: Java processors Roedy Green <see_website@mindprod.com.invalid> - 2012-07-08 19:44 -0700
                Re: Java processors Lew <noone@lewscanon.com> - 2012-07-09 23:41 -0700
                Re: Java processors David Lamb <dalamb@cs.queensu.ca> - 2012-07-16 13:22 -0400
                Re: Java processors Lew <lewbloch@gmail.com> - 2012-07-16 14:03 -0700
                Re: Java processors Roedy Green <see_website@mindprod.com.invalid> - 2012-07-08 19:42 -0700
                Re: Java processors Daniele Futtorovic <da.futt.news@laposte-dot-net.invalid> - 2012-07-10 01:13 +0200
                Re: Java processors Lew <lewbloch@gmail.com> - 2012-07-09 16:26 -0700
                Re: Java processors Roedy Green <see_website@mindprod.com.invalid> - 2012-07-11 15:41 -0700
                Re: Java processors Daniele Futtorovic <da.futt.news@laposte-dot-net.invalid> - 2012-07-12 01:02 +0200
                Re: Java processors Wanja Gayk <brixomatic@yahoo.com> - 2012-07-21 18:46 +0200
                Re: Java processors Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-07-21 13:05 -0400
                Re: Java processors Wanja Gayk <brixomatic@yahoo.com> - 2012-07-21 19:23 +0200
                Re: Java processors Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-07-21 14:10 -0400
                Re: Java processors Wanja Gayk <brixomatic@yahoo.com> - 2012-07-23 01:17 +0200
                Re: Java processors Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-07-22 20:15 -0400
                Re: Java processors Daniele Futtorovic <da.futt.news@laposte-dot-net.invalid> - 2012-07-22 15:13 +0200
                Re: Java processors Roedy Green <see_website@mindprod.com.invalid> - 2012-07-06 19:03 -0700
                Re: Java processors Roedy Green <see_website@mindprod.com.invalid> - 2012-07-08 19:51 -0700
              Re: Java processors Roedy Green <see_website@mindprod.com.invalid> - 2012-07-07 21:17 -0700
                Re: Java processors Lew <noone@lewscanon.com> - 2012-07-07 23:04 -0700
                Re: Java processors Roedy Green <see_website@mindprod.com.invalid> - 2012-07-08 09:29 -0700
                Re: Java processors Lew <noone@lewscanon.com> - 2012-07-08 11:57 -0700
            Re: Java processors Wanja Gayk <brixomatic@yahoo.com> - 2012-07-08 15:40 +0200
              Re: Java processors BGB <cr88192@hotmail.com> - 2012-07-08 10:36 -0500
          Re: Java processors Lew <lewbloch@gmail.com> - 2012-07-06 11:31 -0700
      Re: Java processors Jim Janney <jjanney@shell.xmission.com> - 2012-07-05 13:02 -0600
        Re: Java processors BGB <cr88192@hotmail.com> - 2012-07-05 16:09 -0500
        Re: Java processors Jan Burse <janburse@fastmail.fm> - 2012-07-06 01:29 +0200
          Re: Java processors Martin Gregorie <martin@address-in-sig.invalid> - 2012-07-06 00:42 +0000
            Re: Java processors Roedy Green <see_website@mindprod.com.invalid> - 2012-07-06 13:53 -0700
              Re: Java processors Martin Gregorie <martin@address-in-sig.invalid> - 2012-07-06 21:18 +0000
                Re: Java processors Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-07-06 18:17 -0400
                Re: Java processors Martin Gregorie <martin@address-in-sig.invalid> - 2012-07-06 22:29 +0000
                Re: Java processors Roedy Green <see_website@mindprod.com.invalid> - 2012-07-06 19:10 -0700
                Re: Java processors BGB <cr88192@hotmail.com> - 2012-07-07 09:42 -0500
                Re: Java processors Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-07-07 10:58 -0400
                (OT) Was: Re: Java processors Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-07-07 11:38 -0400
                Re: (OT) Was: Re: Java processors Gene Wirchenko <genew@ocis.net> - 2012-07-07 21:19 -0700
                Re: (OT) Was: Re: Java processors "Peter J. Holzer" <hjp-usenet2@hjp.at> - 2012-07-08 12:15 +0200
                Re: Java processors Gene Wirchenko <genew@ocis.net> - 2012-07-07 21:17 -0700
          Re: Java processors Jim Janney <jjanney@shell.xmission.com> - 2012-07-05 19:14 -0600
        Re: Java processors Roedy Green <see_website@mindprod.com.invalid> - 2012-07-06 13:34 -0700
          Re: Java processors Jan Burse <janburse@fastmail.fm> - 2012-07-06 23:04 +0200
            Re: Java processors Silvio Bierman <silvio@moc.com> - 2012-07-07 00:13 +0200
              Re: Java processors Roedy Green <see_website@mindprod.com.invalid> - 2012-07-06 19:16 -0700
                Re: Java processors "Peter J. Holzer" <hjp-usenet2@hjp.at> - 2012-07-08 11:37 +0200
      Re: Java processors Roedy Green <see_website@mindprod.com.invalid> - 2012-07-06 13:24 -0700
        Re: Java processors BGB <cr88192@hotmail.com> - 2012-07-07 10:06 -0500
  Re: Java processors Roedy Green <see_website@mindprod.com.invalid> - 2012-07-06 05:22 -0700

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