Re: starting collection, reason stop the world collection

Hi Walden,

Interesting. I'm wondering how it does that.

You'd have to ask the right people at IBM about the details, but the
claim is that it's unique among garbage collectors. It certainly causes
consternation among other Java folk who come at me with suggestions about
gc. They tend to think I'm stupid when I tell them it won't work on the
400; until they completely mess things up.

But I suspect it has something to do with what the the "i" stands for in
AS/400. For those not in the know (and yes, I understand I'm supposed to
say iSeries or i, or name du jour,) it stands for "integrated".

However, either because it doesn't work well enough or, more likely, due
to economies of scale, my understanding is that the classic JVM and its gc
are on the way out in favor of generational garbage collectors like everyone
else. The 32 bit JVM is already there.

BTW, the 32 bit JVM makes more and more sense to me, especially after talking with some developers on the Apple boards. Should be able to serve a lot of users with 4 gig. I just haven't had the opportunity to use it in a production situation yet.


Joe Sam

Joe Sam Shirah - http://www.conceptgo.com
conceptGO - Consulting/Development/Outsourcing
Java Filter Forum: http://www.ibm.com/developerworks/java/
Just the JDBC FAQs: http://www.jguru.com/faq/JDBC
Going International? http://www.jguru.com/faq/I18N
Que Java400? http://www.jguru.com/faq/Java400

----- Original Message ----- From: "Walden H. Leverich" <WaldenL@xxxxxxxxxxxxxxx>
To: "Java Programming on and around the iSeries / AS400"
<java400-l@xxxxxxxxxxxx>
Sent: Wednesday, March 04, 2009 2:38 PM
Subject: RE: starting collection, reason stop the world collection

That means other work goes on during a collection.

Interesting. I'm wondering how it does that. I can see the actual
cleanup occurring while other work is going on, but how does it identify
the garbage to be cleaned up w/out suspending the other threads. If the
thread is running, the reference to the object could be in a CPU
register, how would GC know about it? I'm not deeply familiar w/Java's
GC, but I am w/.NET's and there is a momentary stop of all threads when
GC kicks in... we're talking microseconds, but it's there.

-Walden

--
Walden H Leverich III
Tech Software
(516) 627-3800 x3051
WaldenL@xxxxxxxxxxxxxxx
http://www.TechSoftInc.com

Quiquid latine dictum sit altum viditur.
(Whatever is said in Latin seems profound.)

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