dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Tue, Mar 29, 2011 at 11:10:17PM -0700, Johan Hake wrote:
> What triggers the error? Is it writing and/or reading to/from file. Is it
> assignment of data from within the read function in the test?
>
> johan

It's the next line following the read:

  std::string filename(p1["filename"]);

So something goes wrong for at least one of the processes when the
parameters are read back from file. Here's what happens:

1. All processes create parameter set p0

2. Process 0 writes p0 to file

3. Everyone waits (barrier)

4. All processes read from the file into p1

5. All processes access parameters from p1 and compare to p0

--
Anders



> On Tuesday March 29 2011 22:53:01 Anders Logg wrote:
> > The parameter unit test is sometimes failing in parallel. On my local
> > machine it always seems to work with 2 or 3 processes, but sometimes
> > it fails with 4, giving the same error message as the buildbot:
> >
> > ##Failure Location unknown## : Error
> > Test name: InputOutput::test_simple
> > uncaught exception of type St13runtime_error
> > - *** Error: Unable to access parameter "filename" in parameter set
> > "test", par
> > ameter not defined.
> >
> > Failures !!!
> > Run: 2   Failure total: 1   Failures: 0   Errors: 1
> >
> > There is a check for which process writes to file and a barrier that
> > should make sure everyone waits until the file gets written.
> >
> >   // Save to file
> >   if (dolfin::MPI::process_number() == 0)
> >   {
> >     File f0("test_parameters.xml");
> >     f0 << p0;
> >   }
> >   dolfin::MPI::barrier();
> >
> >   // Read from file
> >   Parameters p1;
> >   File f1("test_parameters.xml");
> >   f1 >> p1;
> >
> > I thought that should do the trick, but apparently not.
> >
> > Any ideas what goes wrong?
> >