[Developers] CactusExternal/HDF5 is dangerous

Erik Schnetter schnetter at aei.mpg.de
Fri Apr 29 05:01:53 CDT 2005

On Wednesday 27 April 2005 11:56, Thomas Radke wrote:
> Erik Schnetter wrote:
> > I used CactusExternal/HDF5 to configure with HDF5, and I find that
> > it runs the configuration script at compile time instead of at
> > configuration time.  This is dangerous.  When a system
> > administrator installs a new version of the HDF5 library, thorn
> > HDF5 might pick it up and silently change which version of HDF5 the
> > code is compiled against. This can lead to inconsistencies that are
> > next to impossible to detect and which can lead to segmentation
> > faults.
> >
> > A configuration script needs to run at configuration time; the
> > configuration settings must stay constant at compile time.
> Thorn configuration scripts listed in configuration.ccl files are run
> at CST time, ie. every time the thornlist changes or a rebuild is
> forced. The information added by those configuration scripts is saved
> in the configuration's makefile snippets which are included when
> actually compiling the thorn(s).
> Why shouldn't this be enough ?

I am used to the idea that the libraries are chosen together with the 
compiler etc. at configuration time.  That means that you can re-build 
your executable as often as possible without changing the 

The CST stage is run very often, each time a thorn is added or a *.ccl 
file is changed.  It is bad if this can change the configuration.  Once 
I have selected a certain version of the HDF5 library, I want to stick 
with it, no matter what other software is installed on the system or in 
my home directory.  For example, changing the HDF5 library might 
require a recompilation from scratch.  If the HDF5 library is suddenly 
changed, the executable may either not link or crash at run time.


Erik Schnetter <schnetter at aei.mpg.de>   http://www.aei.mpg.de/~eschnett/

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