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From: Erik Groeneveld <erik@cq2.nl>
Date: Sun, 03 Apr 2011 17:15:00 -0000
Message-ID: <BANLkTinjau9wC4Fe36U7WMqP5n_+kEtdGA@mail.gmail.com>
Subject: Re: GC leaks debugging
To: "Boehm, Hans" <hans.boehm@hp.com>
Cc: Andrew Haley <aph@redhat.com>, "java@gcc.gnu.org" <java@gcc.gnu.org>
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On Sat, Apr 2, 2011 at 11:38 AM, Erik Groeneveld <erik@cq2.nl> wrote:
>
>> Note that in the information you posted, the GC was scanning around 7.5M=
B of roots conservatively. =C2=A0It might be worth checking what those regi=
ons are.
> It seems it come from libgcj. =C2=A0This is now my minimal program:
>
> #include <gcj/cni.h>
> void _Jv_RunGC(void);
> int main(int argc, char *argv[]) {
> =C2=A0 =C2=A0JvCreateJavaVM(NULL);
> =C2=A0 =C2=A0_Jv_RunGC();
> =C2=A0 =C2=A0//JvAttachCurrentThread(NULL, NULL);
> }

With GC_DUMP_REGULARLY it logs an empty heap just before
JvCreateJavaVM and right after it:

***Static roots:
=46rom 0x8049bdc to 0x8049d34  (temporary)
=46rom 0xb714c000 to 0xb787dcdc  (temporary)
Total size: 7544372

Using gc-analyse's memory map, I find the first root to be in this
block of 4 kB. Probably my own data segment or stack:
8049000-804a000 -> .../minimal/test offset 0

The second root spans the next block of 6792 kB and most of the
following block of 584 kB:

b714c000-b77ee000 -> .../gccinstall-def/lib/libgcj.so.12.0.0 offset 1b3a000
b77ee000-b7880000 -> TestDump001.bytes offset b0009c

The heap itself is only 368 kB and contains lots of static strings,
classes etc. Nothing special AFAICS.

So I am now off into JvCreateJavaVM, if you have any thoughts, please
let me know.
Erik