On Tuesday March 29 2011 23:27:27 Anders Logg wrote:
> 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"]);
It took some time to find the parameter unit test ;)
> 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
I guess it is 4 that goes wrong. I have tried to google varieties of "open
shared file fstream". It looks like others have had the same problem.
Johan
>
> --
> 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?
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