PETScVector::init should not take comm as an argument

[Jan Blechta]

This fails on two processes:

from dolfin import*
vec = PETScVector()
vec.init(mpi_comm_self(), 1)
assert vec.mpi_comm() == mpi_comm_self()

As a result PETScVector::gather which uses init() does not work properly. See, https://groups.google.com/forum/#!topic/fenics-support/C3uIwxMGhws, thanks Giorgos Grekas for reporting.

Moreoever the condition on y.mpi_comm() here looks incorrect.

[Prof Garth Wells]

The bug is that PETSc::init shouldn't take a communicator. The underlying PETSc object is created in the constructor, and this is when the communicator is set.

Use in the report is incorrect. Correct usage is:

from dolfin import *

# create  communicator

vec = PETScVector(comm)
vec.init(mpi_comm_self(), 1)  # PETSc::init should be fixed to not require a communicator
assert vec.mpi_comm() == mpi_comm_self()

[Jan Blechta]

Ok. This check needs to be called in any case, not just when !_y.empty(), and fixed (dolfin::MPI::size(y.mpi_comm()) is incorrect.)

[Jan Blechta]

I'll fix gather now and keep PETScVector::init for later.

[Jan Blechta]

Fix for gather in https://bitbucket.org/fenics-project/dolfin/branch/jan/fix-petsc-vec-gather#diff. @garth-wells, can you overlook it?

[Jan Blechta]

Fixes in master: 798379a and d2fe9f3. PETScVector::gather will now only accept local gather vector.

Remains to remove comm arg from PETScVector::init.

[Prof Garth Wells]

Fix issue #789.

→ <<cset c0fdc4da7a0a>>

[Jan Blechta]

Forgotten call to TpetraVector::init(comm, N) here: https://bitbucket.org/fenics-project/dolfin/src/8373103148eb09b7f96b19e440215467447c4e9a/dolfin/la/TpetraVector.cpp?at=master&fileviewer=file-view-default#TpetraVector.cpp-44

[Prof Garth Wells]

I confess that it wasn't exactly forgotten. I don't have Trilinos installed, and the wrappers are in too poor shape for me to have had a go blind.

We need to have test coverage for the Trilinos backend, or remove it. @chris_richardson ?

[Chris Richardson]

I have made a fix in a branch. Maybe we can get a cutdown trilinos into bamboo.