[firedrake] Installing Firedrake on an HPC machine

[Lawrence Mitchell]

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On 06/08/15 15:26, Justin Chang wrote:
> Lawrence,
> 
>> mpiexec -n 2 python no-fork.py
> 
> 2
> 
> 2

OK, good.

>> mpiexec -n 2 python fork-before.py
> 
> child exiting
> 
> child exiting
> 
> 2
> 
> 2

Also good.

>> mpiexec -n 2 python fork-after.py
> 
> 2
> 
> 2
> 
> child exiting
> 
> child exiting
> 
> --------------------------------------------------------------------------
>
>  An MPI process has executed an operation involving a call to the
> 
> "fork()" system call to create a child process.  Open MPI is
> currently
> 
> operating in a condition that could result in memory corruption or
> 
> other system errors; your MPI job may hang, crash, or produce
> silent
> 
> data corruption.  The use of fork() (or system() or other calls
> that
> 
> create child processes) is strongly discouraged.
> 
> 
> The process that invoked fork was:
> 
> 
> Local host:          compute-0-0 (PID 43057)
> 
> MPI_COMM_WORLD rank: 0
> 
> 
> If you are *absolutely sure* that your application will
> successfully
> 
> and correctly survive a call to fork(), you may disable this
> warning
> 
> by setting the mpi_warn_on_fork MCA parameter to 0.
> 
> --------------------------------------------------------------------------
>
>  [compute-0-0.local:43055] 1 more process has sent help message 
> help-mpi-runtime.txt / mpi_init:warn-fork
> 
> [compute-0-0.local:43055] Set MCA parameter
> "orte_base_help_aggregate" to 0 to see all help / error messages

As expected, we fork()ed after MPI_Init and so OpenMPI complains.

>> mpiexec -n 2 python closer-test.py
> 
> In parent True
> 
> In parent True
> 
> In child False
> 
> In child False

OK good, so if we fork before MPI_Init then OpenMPI doesn't complain.

>> mpiexec -n 2 python fork-pyop2.py
> 
> 2
> 
> 2

So this one just does the same as before, but using the PyOP2-internal
"early fork", so that works too.

> 
> The last three examples pyop2.py, import-firedrake.py, and 
> firedrake-test.py did not run because they say "ImportError:
> cannot import name op2". And now all of my firedrake programs run
> into this exact error, which is confusing.

Ah the pyop2.py example was badly named.  If you rename it to
run-pyop2.py and do mpiexec -n 2 python run-pyop2.py I hope things
work again.  What's happened is that this file, with name "pyop2" is
now in your pythonpath and python when trying to import pyop2 looks in
this file for all the symbols rather than the proper PyOP2 package.
Can you do that and then try again?

Lawrence
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