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Are there any Garbage Collector improvements?

 
 
Tom Anderson
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      11-21-2008
On Fri, 21 Nov 2008, J. Davidson wrote:

> Tom Anderson wrote:
>> I think only C-style memory managers, which put each deleted block on a
>> free list, do work proportional to dead objects.

>
> I recall reading about garbage collectors that did so as well. I
> definitely recall old Java versions performing better if you reused
> objects rather than discarded them -- exactly opposite to current Java.
> About the latter you seem to be in agreement.


Yes, absolutely. I think this was due to their slow implementation of
allocation, rather than their doing per-dead-object work. I think.

tom

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a moratorium on the future
 
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Roedy Green
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      11-21-2008
On 14 Nov 2008 18:58:27 GMT, http://www.velocityreviews.com/forums/(E-Mail Removed) (Mark Sizzler) wrote,
quoted or indirectly quoted someone who said :

>We have problems with the Java Garbage Collector.
>It is very slow when we hold large tables in memory and perform many inserts and updates.


Others will tackle your problem directly. Here are some things to
check before you invest big bucks in new GC package.

Have you instrumented to be sure the problem is GC? not the
operations on the tables themselves?

Does your table technique keep allocating new objects frequently? It
should be doing something like ArrayList does, using a buffer bigger
than needed and only growing it when it overflows.

Have you done a study of the objects to make sure there is no
packratting? No GC is going to work well if you accidentally hold on
to objects you don't really need. see
http://mindprod.com/jgloss/packratting.html

Finally there is the ballerina in phone booth problem. What is your
ratio of live object space to heap space? No GC will work well when
that ratio gets too large.

--
Roedy Green Canadian Mind Products
http://mindprod.com
Your old road is
Rapidly agin'.
Please get out of the new one
If you can't lend your hand
For the times they are a-changin'.
 
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Tom Anderson
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      11-21-2008
On Fri, 21 Nov 2008, Roedy Green wrote:

> On 14 Nov 2008 18:58:27 GMT, (E-Mail Removed) (Mark Sizzler) wrote,
> quoted or indirectly quoted someone who said :
>
>> We have problems with the Java Garbage Collector.

>
> Finally there is the ballerina in phone booth problem.


I hadn't heard it called that before. That's a great name!

tom

--
A paranoid-schizophrenic is a guy who just found out what's going on. --
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