[gambit-list] Dumping the heap

Dimitris Vyzovitis vyzo at hackzen.org
Fri Feb 2 07:49:14 EST 2018


it would be nice to have a primitive to do this for Scheme procedures!
Something like (on-all-processors thunk) would be awesome.

-- vyzo

On Fri, Feb 2, 2018 at 2:41 PM, Marc Feeley <feeley at iro.umontreal.ca> wrote:

> Yes each processor has its own still_objs list and to account for all
> still objects you must iterate over the processors.  In order to avoid
> modification of the still_objs lists while doing this the best approach is
> to use the barrier operation mechanism.  That way all processors (but one)
> will be idle while iterating (or you could have all processors cooperate).
> This is done with the “on_all_processors” function.  For an example, check
> out ___garbage_collect or ___fdset_resize in lib/setup.c .
>
> Marc
>
>
>
> > On Feb 2, 2018, at 6:23 AM, Dimitris Vyzovitis <vyzo at hackzen.org> wrote:
> >
> > Relevant code for accounting still objects:
> > https://gist.github.com/vyzo/ab4219382c0870779991d4c701921d2c
> >
> > The limitation is that the still_objs_ is per processor, and not vm-wide.
> > Does that mean we would have to crawl all processors in SMP?
> >
> > -- vyzo
> >
> >
> > On Thu, Feb 1, 2018 at 3:16 PM, Marc Feeley <feeley at iro.umontreal.ca>
> wrote:
> > > On Feb 1, 2018, at 8:06 AM, Dimitris Vyzovitis <vyzo at hackzen.org>
> wrote:
> > >
> > > thanks Guillaume!
> > >
> > > this is a great start for me -- i am helping fare debug a memory leak,
> and it's really hard to identify
> > > without dumping the heap to see what kind of object is leaking.
> >
> > For your information I discovered a few memory leaks with the networking
> functions.  They were due to “sockaddr” structures being converted to
> “still” Scheme objects with a reference count = 1, but the reference count
> was never decremented (with ___release_scmobj).  This has been fixed in the
> recent UDP commit.
> >
> > I believe that this kind of situation might exist in other places in the
> runtime system.  So it might be useful to debug this to have a function
> that returns a list of all the “still” Scheme objects that have a reference
> count != 0.  This should be easy to write… the GC maintains a list of the
> still objects in the C variable “still_objs”.
> >
> > So the idea would be to check at the end of a program if there are any
> still objects with non-zero ref counts.
> >
> > Marc
> >
> >
>
>
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