Re: [Condor-users] Standard universe python: dynamic library problem

[Colin Dewey <cdewey@xxxxxxxxxxxxxxxx>]

Thanks, Daniel.  I have very little experience with dynamic linking,  
but I can't help but wonder: in the standard universe, filesystem  
operations use a remote system call mechanism, and since dynamic  
libraries are just files, wouldn't these also be loaded from the  
remote submit node?  If this were the case, then the glibc versions  
are always the same because they are from the same machine?

Thanks,
Colin

On May 26, 2007, at 10:45 PM, Daniel Forrest wrote:

> Colin,
>
> > I have been trying to get Python compiled for the standard universe,
> > as was claimed possible in:
> >
> > https://lists.cs.wisc.edu/archive/condor-users/2007-March/ 
> > msg00217.shtml
> > https://lists.cs.wisc.edu/archive/condor-users/2005-August/
> > msg00061.shtml
> >
> > Unfortunately, I am encountering linking problems when using
> > condor_compile that relate to dynamic linking library (libdl.a).  I
> > get a bunch of undefined references to functions in that library (see
> > below).  I am using RHEL 4 with condor v6.8.4 (RHEL 3), gcc 3.4.6,
> > and python 2.3.6 (also tried python 2.5.1 without success).  I
> > realize that Condor does not support checkpointing for Linux programs
> > that do dynamic linking, but I believe the program should at least
> > link properly (and be usable without the checkpointing feature).
> >
> > Any help would be greatly appreciated.
>
> Trust me, you don't want to go there.  There are serious problems with
> using dlopen in statically linked programs.
>
> > libpython2.3.a(dynload_shlib.o)(.text+0x15d): In function  
> > `_PyImport_GetDynLoadFunc':
> > Python/dynload_shlib.c:129: warning: Using 'dlopen' in statically
> > linked applications requires at runtime the shared libraries from the
> > glibc version used for linking
>
> This warning message is telling you what the problem is.  Even if
> dlopen were available, it requires that the machine where your program
> runs has the same glibc version installed as the one you built on.
> As I understand it, the dlopen in the static program might work to
> load a dynamic object, but if that object loads another one it would
> use the dynamic dlopen and the version mismatch causes a crash.
>
> What you want to do is configure a python that doesn't use dynamic
> loading, but instead has the modules you need already built in.  I
> have done this with perl and I see no reason why it wouldn't work with
> python.  Here is a link I found about that very topic:
>
> http://www.thescripts.com/forum/thread34240.html
>
> --
> Daniel K. Forrest	Laboratory for Molecular and
> forrest@xxxxxxxxxxxxx	Computational Genomics
> (608) 262 - 9479	University of Wisconsin, Madison