Re: Any word on large heap support

• Subject: Re: Any word on large heap support
• From: "John W. Whitworth" <email@hidden>
• Date: Fri, 30 Apr 2004 00:49:10 +0100

On Apr 29, 2004, at 12:14 PM, Michael Latta wrote (off list):

Can GCJ handle run-time class loaders? We use that extensively. We also need to run on PCs.

Michael

On Apr 29, 2004, at 9:09 AM, Joshua Smith wrote (off list):

Have you tried compiling with GCJ? I don't know whether it has those limitations...

On Apr 29, 2004, at 1:51 AM, Michael Latta wrote:

Yes I know. It just kills me to have 4GB of ram and get "OutOfMemoryError" all the time!! So I filed an enhancement request.

Michael

I just learned about gcj recently from this list, so I don't know much. I have read that it works on PC, Mac and Linux, and a quick experiment I did on linux (it's bundled with Red Hat) confirmed that Class.forName does the right thing. From what I've read, AWT peers are not available, so people doing GUI work have been getting by with SWT.

I just did a quick test on Linux using this program:

public class mt
{
public static void main(String args[])
{
int [][] mem = new int[1000][];
for (int i=0;i<1000;++i)
{
mem[i] = new int[1024*1024*32];
System.err.println(Runtime.getRuntime().totalMemory());
}
}
}

I got this output:

[jesmith]$ gcj -o mt --main=mt mt.java
[jesmith]$ ./mt
134619136
268972032
403324928
537677824
672030720
806383616
940736512
1091735552
GC Warning: Repeated allocation of very large block (appr. size 134221824):
May lead to memory leak and poor performance.
1242734592
1393733632
1544732672
1691021312
1837309952
GC Warning: Repeated allocation of very large block (appr. size 134221824):
May lead to memory leak and poor performance.
1983598592
2129887232
-2018791424
-1872502784
-1727295488
GC Warning: Repeated allocation of very large block (appr. size 134221824):
May lead to memory leak and poor performance.
-1582088192
-1436880896
GC Warning: Out of Memory! Returning NIL!

So it appears that there is no artificial 2 GB limit. Perhaps someone who has GCJ on their Mac could run this test for us, and see what happens?

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