I looked a bit more, and it seems more complicated that that. You're
right about atexit(), but PyTrilinos actually does the right thing wrt
initialisation (it checks MPI_Initialized, and does nothing if already
initialised). Hence, this does not explain the failures before exit(). I
managed to tease out this error message from trilinos with the "wrong"
import order, but it's not helpful:
Error! An attempt was made to access parameter "aggregation: type" of type
"string"
in the parameter (sub)list "ML preconditioner"
using the incorrect type "string"!
The visible error, after the above is caught and re-thrown, is
*********************************************************
ML failed to compute the multigrid preconditioner. The
most common problem is an incorrect data type in ML's
parameter list (e.g. 'int' instead of 'bool').
Note: List.set("ML print initial list",X) might help
figure out the bad one on pid X.
*********************************************************
ML::ERROR:: -1,
/home/jobh/src/fenics/trilinos-10.6.2-Source/packages/ml/src/Utils/ml_MultiLevelPreconditioner.cpp,
line 1694
It ran clean under valgrind, so any stack or heap smash is subtle. I
don't think I'll dig any deeper, given that the workaround is so simple.
(I added the following in dolfin, to get rid of the MPI abort, but it
didn't help with the problem above of course:)
diff --git a/dolfin/main/SubSystemsManager.cpp
b/dolfin/main/SubSystemsManager.cpp
index 52c8982..6a19e4f 100644
--- a/dolfin/main/SubSystemsManager.cpp
+++ b/dolfin/main/SubSystemsManager.cpp
@@ -126,7 +126,10 @@ void SubSystemsManager::finalize_mpi()
//Finalise MPI if required
if (MPI::Is_initialized() and sub_systems_manager.control_mpi)
{
- MPI::Finalize();
+ if (MPI::Is_finalized())
+ warning("MPI::Finalize has been called by someone else (how rude)");
+ else
+ MPI::Finalize();
sub_systems_manager.control_mpi = false;
}
--
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https://bugs.launchpad.net/bugs/705401
Title:
When PyTrilinos is imported after dolfin, bad things happen
Status in DOLFIN:
New
Bug description:
When using PyTrilinos (ML in particular), the order of imports is
important. If dolfin is imported first, it crashes at exit, and there
are problems also with constructing preconditioners etc.
It looks like it has to do with MPI initialisation, but I haven't
looked at it closely.
A simple workaround may be to try an import ML in dolfin/__init__.py
(just import, not expose) so that it gets initialised. I don't know if
the performance hit is worth it. It would of course be better to find
a proper fix.
Otherwise, it's nice to have it documented here. For google::
>>> import dolfin
>>> from PyTrilinos import ML
>>> exit()
*** An error occurred in MPI_Finalize
*** after MPI was finalized
*** MPI_ERRORS_ARE_FATAL (your MPI job will now abort)
[rodin:17864] Abort after MPI_FINALIZE completed successfully; not able to
guarantee that all other processes were killed!
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