Re: [h5md-user] Strings again / parallel issue

[Pierre de Buyl]

On Tue, Feb 04, 2014 at 11:26:32PM -0500, Peter Colberg wrote:
> On Tue, Feb 04, 2014 at 02:16:37PM -0500, Peter Colberg wrote:
> > On Tue, Feb 04, 2014 at 07:42:19PM +0100, Pierre de Buyl wrote:
> > > Check the other file, parallel_string_attribute.f90. The call to 
> > > h5awrite_f is
> > > done on every rank. And it writes the attribute correctly. The program
> > > parallel_vl_string_attribute.f90 does not execute properly.
> > 
> > You are right; HDF5 mandates calling H5Awrite from all processes:
> > 
> > http://www.hdfgroup.org/HDF5/doc/RM/CollectiveCalls.html
> > 
> > “Because raw data for an attribute is cached locally, all processes
> > must participate in order to guarantee that future H5Aread calls
> > return correct results on all processes.”
> 
> Good news: collective writing and reading of attributes of
> variable-length string type is working fine here.
> 
> I attached a test case. Unfortunately, this is not very helpful to
> you at the moment, since MPI for Lua is not published yet :-(. The
> test passes on Debian jessie using HDF5 1.8.12, and Open MPI 1.6.5
> or MPICH 3.0.4, spawned with "mpirun -np 8" onto a single machine.
> 
> I will try Pierre's Fortran example next.

On the Fortran examples page on the HDF5 website [1] there is simply no
variable-length string attribute code :-/

Although it seems that I am the only Fortran user currently on the list, has
someone else feedback on this?

P

[1] http://www.hdfgroup.org/HDF5/examples/api18-fortran.html