public inbox for java@gcc.gnu.org
 help / color / mirror / Atom feed
From: abhishek desai <abhi00@gmail.com>
To: java@gcc.gnu.org
Cc: Andrew Haley <aph@redhat.com>
Subject: Re: Using libgcj with different memory management library.
Date: Mon, 08 Jun 2009 09:43:00 -0000	[thread overview]
Message-ID: <898285d30906080243o70b109a0g54a6b3b00a87f4d2@mail.gmail.com> (raw)
In-Reply-To: <4A2CD546.7030603@redhat.com>

> I don't understand how this can work.  The gc is a memory manager; how
> can it use some other memory manager to do its own work?  You'll have
> to explain a little more.

From what I understand GC uses GC_unix_get_mem to allocate memory
which calls mmap on /dev/zero on my system. This memory is managed by
GC for object allocation and also for GC internal working. I hope this
is correct. What I want to do is replace the mmap with my_malloc call
which will return a pointer to the allocated memory. my_malloc will
allocate memory from an internal fixed memory pool.

On Mon, Jun 8, 2009 at 2:39 PM, Andrew Haley<aph@redhat.com> wrote:
> abhishek desai wrote:
>
>> 1. As per my understanding libgcj uses boehm garbage collector for
>> memory allocations. Are there any allocations in libgcj which are
>> not routed to the garbage collector ? specially the parts of the
>> library written in C++. From what I understand is that the memory
>> allocated with the 'new' operator are routed to the gc .
>
> Not exactly.  If you have a Java class, i.e. one which inherits from
> java.lang.Object, then its new uses the GC.
>
>> Is it necessary that the class of object being allocated should be
>> derived from the 'object' class for it to be allocated on the gc ?
>> or all the allocations with new get routed to gc ?
>> http://gcc.gnu.org/onlinedocs/gcj/Object-allocation.html#Object-allocation
>
> Yes, it is.  Of course, you can always overload new in your own classes
> to use the Boehm gc, evernif they don't derive from Object.  You'll
> have to make sure they're marked correctly, though.
>
>> 2. I have a memory manager which allocates memory from a specific
>> memory pool. I want to port boehm gc to use this memory manager for
>> its allocations.
>
> I don't understand how this can work.  The gc is a memory manager; how
> can it use some other memory manager to do its own work?  You'll have
> to explain a little more.
>
>> Can someone give me some pointers as to where I can make the
>> necessary modifications ? I can see the gcconfig.h and os_dep.c is
>> the file containing the final system memory allocation calls.  Is
>> there some other place I need to look at ? Are there any tricky
>> issues I need to look at while doing the porting ?
>
> You'll need to the gc just to scan your memory pool, or also manage
> it?  Doing the latter will be hard, the former easy.
>
> Andrew.
>
>

  reply	other threads:[~2009-06-08  9:43 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-06-08  7:06 abhishek desai
2009-06-08  9:09 ` Andrew Haley
2009-06-08  9:43   ` abhishek desai [this message]
2009-06-08  9:45     ` Andrew Haley

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=898285d30906080243o70b109a0g54a6b3b00a87f4d2@mail.gmail.com \
    --to=abhi00@gmail.com \
    --cc=aph@redhat.com \
    --cc=java@gcc.gnu.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).