[Dune] GMSH reader fails in parallel case

[Oliver Sander]

Am 14.07.2014 14:54, schrieb Andreas Dedner:
> There has never been a clear decision I think on how the grid readers should work in the
> case that the macro grid is not pre distributed. In ALU the idea is that the grid is distributed
> but in a way that one process has all the elements and the others are empty. Consequently
> only process zero should read the gmsh file and the others should generate an empty grid.
> Now I remember that UG does it differently (requiring) that all process read the full macro grid.
> As I said a place were we need to fix the semantics. DGF does it the ALU way that is why that works
> and gmshreader does in the UG way...
> 
> The simplest way to avoid the issue is to surround the call to the gmshreader by if (rank==0)
> and to construct empty ALUGrids in the else part - but then I assume UG would not be happy....
> 

I don't think so.  UGGrid contains extra code to handle that case.  I don't really know how much
testing it got, though.
--
Oliver

> Andreas
> 
> PS: it would help if you could open a flyspray task with a report, a test program, I could then add
> my 5 cent from above. This would increase the chances that we would actually discuss this
> at the developer meeting in September.
> 
> 
> On 14/07/14 13:00, Sacconi, Andrea wrote:
>> Hi DUNErs,
>>
>> I would like to ask you a question about the GMSH reader for parallel computation (with open-MPI 1.6.5). I am using AlugridSimplex <3,3> for a standard Poisson problem.
>> Everything is fine in the sequential case, while in the parallel case I get the error reported below.
>>
>> as7211 at macomp01:~/dune-2.3.1/dune-bulk/src$ mpirun -n 2 dune_bulk
>> Reading 3d Gmsh grid...
>> Reading 3d Gmsh grid...
>> version 2.2 Gmsh file detected
>> version 2.2 Gmsh file detected
>> file contains 3323 nodes
>> file contains 3323 nodes
>> file contains 19216 elements
>> file contains 19216 elements
>> terminate called after throwing an instance of 'Dune::GridError'
>> [macomp01:03890] *** Process received signal ***
>> [macomp01:03890] Signal: Aborted (6)
>> [macomp01:03890] Signal code:  (-6)
>> [macomp01:03890] [ 0] /lib/x86_64-linux-gnu/libpthread.so.0(+0x10340) [0x7ff363b7b340]
>> [macomp01:03890] [ 1] /lib/x86_64-linux-gnu/libc.so.6(gsignal+0x39) [0x7ff3637dbf79]
>> [macomp01:03890] [ 2] /lib/x86_64-linux-gnu/libc.so.6(abort+0x148) [0x7ff3637df388]
>> [macomp01:03890] [ 3] /usr/lib/x86_64-linux-gnu/libstdc++.so.6(_ZN9__gnu_cxx27__verbose_terminate_handlerEv+0x155) [0x7ff3643056b5]
>> [macomp01:03890] [ 4] /usr/lib/x86_64-linux-gnu/libstdc++.so.6(+0x5e836) [0x7ff364303836]
>> [macomp01:03890] [ 5] /usr/lib/x86_64-linux-gnu/libstdc++.so.6(+0x5e863) [0x7ff364303863]
>> [macomp01:03890] [ 6] /usr/lib/x86_64-linux-gnu/libstdc++.so.6(+0x5eaa2) [0x7ff364303aa2]
>> [macomp01:03890] [ 7]
>> dune_bulk(_ZN4Dune16ALU3dGridFactoryINS_7ALUGridILi3ELi3ELNS_18ALUGridElementTypeE0ELNS_21ALUGridRefinementTypeE1EP19ompi_communicator_tEEE12insertVertexERKNS_11FieldVectorIdLi3EEE+0x1b2) [0x616c82]
>>
>> Any idea about how to use make only the master process read the grid, and not all the processes? In any case, how can the issue be fixed?
>> By the way, if I use DGF reader everything runs fine, both in the sequential and parallel case.
>>
>> Thanks in advance!
>> Andrea
>> __________________________________________________________
>>
>> Andrea Sacconi
>> PhD student, Applied Mathematics
>> AMMP Section, Department of Mathematics, Imperial College London,
>> London SW7 2AZ, UK
>> a.sacconi11 at imperial.ac.uk
>> _______________________________________________
>> Dune mailing list
>> Dune at dune-project.org
>> http://lists.dune-project.org/mailman/listinfo/dune
> 
> 
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