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<p>Dear Steffen,</p>
<p>I thought of changing to dune 2.6 and see if I run into the same
problem.</p>
<p>But now, with dune 2.6 I have another problem. Basically, its
exactly the same test setting as before, but now the linear solver
does not solve in parallel any more.</p>
<p>The only difference between my code in 2.5 and 2.6 versions is in
the vector backend blocking. In 2.5 I had "<font color="#3333ff">using
VBE =
Dune::PDELab::ISTL::VectorBackend<Dune::PDELab::ISTL::Blocking::fixed,
num_of_variables>;</font>"</p>
<p>whereas, in 2.6, I have "<font color="#3333ff">using VBE =
Dune::PDELab::ISTL::VectorBackend<Dune::PDELab::ISTL::Blocking::none>;</font>".</p>
<p>If I try to use a fixed blocking in 2.6, I get the following
error:</p>
<p><font color="#3333ff">/dune/dune-pdelab/dune/pdelab/backend/istl/vectorhelpers.hh:323:9:
error: static assertion failed: You requested static blocking,
but at least one leaf space has a finite element that does not
support automatic block size extraction. Please specify the
block size with the second template parameter of that space's
vector backend.</font></p>
<p>FYI, In dune 2.5, the following linear solver was solving quite
fine:</p>
<p><font color="#3333ff">typedef
Dune::PDELab::ISTLBackend_OVLP_GMRES_ILU0<GFS,CC> LS;<br>
LS ls(gfs,cc,5000,1,200);</font><br>
</p>
<p>But now somehow it does not work. I also tried the following
linear solvers, but none seems to solve...<br>
</p>
<p><font color="#3333ff">typedef
Dune::PDELab::ISTLBackend_BCGS_AMG_SSOR<IGO> LS;<br>
LS ls(gfs,5000,1,true,true);<br>
typedef Dune::PDELab::ISTLBackend_BCGS_AMG_ILU0<IGO> LS;<br>
LS ls(gfs,5000,0, false, true);<br>
typedef Dune::PDELab::ISTLBackend_OVLP_BCGS_SSORk<GFS,CC>
LS;<br>
LS ls(gfs,cc,5000,1,1);</font><br>
</p>
<p>I am not sure what I am doing wrong here, and I'll be really
grateful if somebody can help me out!</p>
<p>Thanks, and best wishes, Shubhangi<br>
</p>
<div class="moz-cite-prefix">On 10.10.18 14:54, Steffen Müthing
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:F2E86362-A482-451E-9044-19A400D5BA0B@iwr.uni-heidelberg.de">
<pre class="moz-quote-pre" wrap="">Hi Shubhangi,
that version contains the fix that makes sure you always get an error message. Does your
program also hang in sequential runs? My next step would probably be to run a debug build
and see if that hangs as well. If it does, I'd attach a debugger to the hanging process to see
where exactly the problem is happening.
Steffen
</pre>
<blockquote type="cite">
<pre class="moz-quote-pre" wrap="">Am 10.10.2018 um 13:07 schrieb Shubhangi Gupta <a class="moz-txt-link-rfc2396E" href="mailto:sgupta@geomar.de"><sgupta@geomar.de></a>:
Hi Stefan,
I am running version 2.5. The program just silently freezes. There are no error messages.
On 10.10.2018 13:05, Steffen Müthing wrote:
</pre>
<blockquote type="cite">
<pre class="moz-quote-pre" wrap="">HI Shubhangi,
</pre>
<blockquote type="cite">
<pre class="moz-quote-pre" wrap="">Am 09.10.2018 um 21:35 schrieb Shubhangi Gupta <a class="moz-txt-link-rfc2396E" href="mailto:sgupta@geomar.de"><sgupta@geomar.de></a>:
Hi Steffen,
Thanks a lot for your reply! This is happening on my laptop, and also on the cluster... hmmm... I am not sure what to do next... DO you maybe have any suggestions?
</pre>
</blockquote>
<pre class="moz-quote-pre" wrap="">what version of Dune are you running? Errors before the start of VTK output are often related to missing
directories for the files, and there were some bug fixes in recent Dune versions. Do you get any kind
of error message, or does the program just silently freeze?
Steffen
</pre>
<blockquote type="cite">
<pre class="moz-quote-pre" wrap="">Thanks again, and best wishes, Shubhangi
On 09.10.2018 21:02, Steffen Müthing wrote:
</pre>
<blockquote type="cite">
<pre class="moz-quote-pre" wrap="">Hi Shubhangi,
</pre>
<blockquote type="cite">
<pre class="moz-quote-pre" wrap="">Am 09.10.2018 um 16:32 schrieb Shubhangi Gupta <a class="moz-txt-link-rfc2396E" href="mailto:sgupta@geomar.de"><sgupta@geomar.de></a>:
Dear all,
I am currently experiencing a really strange problem during the execution of my dune program... When I run the problem in parallel, the program execution freezes in the terminal just before writing the vtk output file... the freeze occurs randomly, sometimes right before the first output, but sometimes after 5, 20, or even 500 outputs, even though I don't change anything about my problem setting! I am really puzzled, and I'll be very thankful for suggestions for solving/debugging this!
</pre>
</blockquote>
<pre class="moz-quote-pre" wrap="">that really sounds strange. The one explanation I can think of is a race condition. Are you running this on a cluster with a network file system?
In that case, there might be an issue where one rank tries to write to a per-timestep subdirectory before the creation of that subdirectory has
been flushed from rank 0 to the file server and the other compute nodes, but that’s just guessing right now (but that might explain the freeze if
the program crash is not properly propagated by your MPI / batch system).
Steffen
</pre>
<blockquote type="cite">
<pre class="moz-quote-pre" wrap="">Thanks in advance, and best wishes, Shubhangi
PS: So far, this problem occurs only in parallel. I write vtk output as follows:
int subsampling = 0;
typedef Dune::SubsamplingVTKWriter<GV> VTKWRITER;
VTKWRITER vtkwriter(gv,subsampling,(int)0);
typedef Dune::VTKSequenceWriter<GV> VTKSEQUENCEWRITER;
VTKSEQUENCEWRITER vtkSequenceWriter( std::make_shared<
VTKWRITER (vtkwriter), fileName, pathName,"" );
.....
.....
vtkSequenceWriter.write(time,Dune::VTK::appendedraw);
--
Dr. Shubhangi Gupta
Marine Geosystems
GEOMAR Helmholtz Center for Ocean Research
Wischhofstraße 1-3,
D-24148 Kiel
Room: 12-206
Phone: +49 431 600-1402
Email:
<a class="moz-txt-link-abbreviated" href="mailto:sgupta@geomar.de">sgupta@geomar.de</a>
_______________________________________________
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</pre>
</blockquote>
</blockquote>
<pre class="moz-quote-pre" wrap="">--
Dr. Shubhangi Gupta
Marine Geosystems
GEOMAR Helmholtz Center for Ocean Research
Wischhofstraße 1-3,
D-24148 Kiel
Room: 12-206
Phone: +49 431 600-1402
Email: <a class="moz-txt-link-abbreviated" href="mailto:sgupta@geomar.de">sgupta@geomar.de</a>
</pre>
</blockquote>
</blockquote>
<pre class="moz-quote-pre" wrap="">
--
Dr. Shubhangi Gupta
Marine Geosystems
GEOMAR Helmholtz Center for Ocean Research
Wischhofstraße 1-3,
D-24148 Kiel
Room: 12-206
Phone: +49 431 600-1402
Email: <a class="moz-txt-link-abbreviated" href="mailto:sgupta@geomar.de">sgupta@geomar.de</a>
</pre>
</blockquote>
<pre class="moz-quote-pre" wrap="">
</pre>
</blockquote>
<pre class="moz-signature" cols="72">--
Dr. Shubhangi Gupta
Marine Geosystems
GEOMAR Helmholtz Center for Ocean Research
Wischhofstraße 1-3,
D-24148 Kiel
Room: 12-206
Phone: +49 431 600-1402
Email: <a class="moz-txt-link-abbreviated" href="mailto:sgupta@geomar.de">sgupta@geomar.de</a></pre>
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