Re: Permanent Generation and garbage collection

From:

Joshua Cranmer <Pidgeot18@verizon.invalid>

Newsgroups:

comp.lang.java.programmer

Date:

Wed, 12 Aug 2009 18:13:47 -0400

Message-ID:

<h5vequ$p4u$1@news-int2.gatech.edu>

Tassilo Horn wrote:

For the custom ClassLoader I do count object creations and finalizations
now. And indeed, after I dropped the last reference to some class
loader (at least in my code, dunno if there are references to it in the
JVM internals), the finalize() method isn't called. So I guess, there
are still references to the classes it loaded, or to objects of those
classes.

Using finalize() can wreak havoc with garbage collection: at they very
least, it requires two collection attempts to actually clear the memory.
I have to imagine that for the purposes of unloading storage space for
classes, it will require many more, probably more than the garbage
collector will care to attempt in memory pressure situations.

If you play around with java.lang.ref, you can avoid some potential
finalize() problems, although I don't know how well reference queues
work in this regard.

--
Beware of bugs in the above code; I have only proved it correct, not
tried it. -- Donald E. Knuth