[petsc-users] Proper way to abort/restart SNESSolve due to exceptions

[Zou, Ling]

Hi All,

I have done some researching in the PETSc email archive, but did not find a
decent way to do it. Assume that, during a SNESSolve, something unphysical
happening and a C++ exception is send,  and now I want to stop the
SNESSolve and let it try a smaller time step.
Here are some pseudo code I have:

while(no_converged)
{
  try
  {
    SNESSolve(...);
    if (SNESSolve converged)
      no_converged = false;
  }
  catch(int err)
  {
    /* do some clean work here? */
    dt = 0.5 * dt;
  }
}

It seems to me that it is not a good way to do, as if an exception is
thrown during SNESSolve, the code go to the error catching, changing time
step, and *immediately* do SNESSolve again. I would expect that there
should be some clean work needed before another SNESSolve call, as I
commented in the code.

I found two related email threads:
http://lists.mcs.anl.gov/pipermail/petsc-users/2014-August/022597.html
http://lists.mcs.anl.gov/pipermail/petsc-users/2015-February/024367.html

But I don't see a clear answer there.
Any comments on this issue?

Best,

Ling
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