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Subject: Re: [OMPI devel] Dynamic languages, dlopen() issues, and symbol visibility of libtool ltdl API in current trunk
From: Josh Hursey (jjhursey_at_[hidden])
Date: 2009-09-17 11:16:10

So I started down this road a couple months ago. I was using the
lt_dlopen() and friends in the OPAL CRS self module. The visibility
changes broke that functionality. The one solution that I started
implementing was precisely what you suggested, wrapping a subset the
libtool calls and prefixing them with opal_*. The email thread is below:

The problem that I hit was that libtool's build system did not play
well with the visibility symbols. This caused dlopen to be disabled
incorrectly. The libtool folks have a patch and, I believe, they are
planning on incorporating in the next release. The email thread is

So we would (others can speak up if not) certainly consider such a
wrapper, but I think we need to wait for the next libtool release
(unless there is other magic we can do) before it would be usable.

Do others have any other ideas on how we might get around this in the
mean time?

-- Josh

On Sep 16, 2009, at 5:59 PM, Lisandro Dalcin wrote:

> Hi all.. I have to contact you again about the issues related to
> dlopen()ing libmpi with RTLD_LOCAL, as many dynamic languages (Python
> in my case) do.
> So far, I've been able to manage the issues (despite the "do nothing"
> policy from Open MPI devs, which I understand) in a more or less
> portable manner by taking advantage of the availability of libtool
> ltdl symbols in the Open MPI libraries (specifically, in libopen-pal).
> For reference, all this hackery is here:
> However, I noticed that in current trunk (v1.4, IIUC) things have
> changed and libtool symbols are not externally available. Again, I
> understand the reason and acknowledge that such change is a really
> good thing. However, this change has broken all my hackery for
> dlopen()ing libmpi before the call to MPI_Init().
> Is there any chance that libopen-pal could provide some properly
> prefixed (let say, using "opal_" as a prefix) wrapper calls to a small
> subset of the libtool ltdl API? The following set of wrapper calls
> would is the minimum required to properly load libmpi in a portable
> manner and cleanup resources (let me abuse of my previous suggestion
> and add the opal_ prefix):
> opal_lt_dlinit()
> opal_lt_dlexit()
> opal_lt_dladvise_init(a)
> opal_lt_dladvise_destroy(a)
> opal_lt_dladvise_global(a)
> opal_lt_dladvise_ext(a)
> opal_lt_dlopenadvise(n,a)
> opal_lt_dlclose(h)
> Any chance this request could be considered? I would really like to
> have this before any Open MPI tarball get released without libtool
> symbols exposed...
> --
> Lisandro Dalcín
> ---------------
> Centro Internacional de Métodos Computacionales en Ingeniería (CIMEC)
> Instituto de Desarrollo Tecnológico para la Industria Química (INTEC)
> Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)
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> Tel/Fax: +54-(0)342-451.1594
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