pymor.tools.mpi

This module provides helper methods to use pyMOR in parallel with MPI.

Executing this module will run event_loop on all MPI ranks except for rank 0 where either a given script is executed:

mpirun -n 16 python -m pymor.tools.mpi /path/to/script

or an interactive session is started:

mpirun -n 16 python -m pymor.tools.mpi

When IPython is available, an IPython kernel is started which the user can connect to by calling:

ipython console --existing file_name_printed_by_ipython.json

(Starting the IPython console directly will not work properly with most MPI implementations.) When IPython is not available, the builtin Python REPL is started.

When event_loop is running on the MPI ranks, call can be used on rank 0 to execute the same Python function (given as first argument) simultaneously on all MPI ranks (including rank 0). Calling quit will exit event_loop on all MPI ranks.

Additionally, this module provides several helper methods which are intended to be used in conjunction with call: mpi_info will print a summary of all active MPI ranks, run_code will execute the given code string on all MPI ranks, import_module imports the module with the given path.

A simple object management is implemented with the manage_object, get_object and remove_object methods. It is the user’s responsibility to ensure that calls to manage_object are executed in the same order on all MPI ranks to ensure that the returned ObjectId refers to the same distributed object on all ranks. The functions function_call, function_call_manage, method_call, method_call_manage map instances ObjectId transparently to distributed objects. function_call_manage and method_call_manage will call manage_object on the return value and return the corresponding ObjectId. The functions method_call and method_call_manage are given an ObjectId and a string as first and second argument and execute the method named by the second argument on the object referred to by the first argument.

Module Contents

class pymor.tools.mpi.ObjectId

Bases: int

A handle to an MPI distributed object.

pymor.tools.mpi.call(method, *args, **kwargs)

Execute method on all MPI ranks.

Assuming event_loop is running on all MPI ranks (except rank 0), this will execute method on all ranks (including rank 0) with positional arguments args and keyword arguments kwargs.

Parameters:

• method – The function to execute on all ranks (must be picklable).

• args – The positional arguments for method.

• kwargs – The keyword arguments for method.

Returns:

The return value of method on rank 0.

pymor.tools.mpi.event_loop()

Launches an MPI-based event loop.

Events can be sent by either calling call on rank 0 to execute an arbitrary method on all ranks or by calling quit to exit the loop.

pymor.tools.mpi.event_loop_settings(auto_launch=True)

Settings for pyMOR’s MPI event loop.

Parameters:

auto_launch – If True, automatically execute event_loop on all MPI ranks (except 0) when pyMOR is imported.

pymor.tools.mpi.function_call(f, *args, **kwargs)

Execute the function f with given arguments.

Intended to be used in conjunction with call. Arguments of type ObjectId are transparently mapped to the object they refer to.

pymor.tools.mpi.function_call_manage(f, *args, **kwargs)

Execute the function f and manage the return value.

Intended to be used in conjunction with call. The return value of f is managed by calling manage_object and the corresponding ObjectId is returned. Arguments of type ObjectId are transparently mapped to the object they refer to.

pymor.tools.mpi.get_object(obj_id)

Return the object referred to by obj_id.

pymor.tools.mpi.import_module(path)

Import the module named by path.

Intended to be used in conjunction with call.

pymor.tools.mpi.launch_event_loop()

pymor.tools.mpi.manage_object(obj)

Keep track of obj and return an ObjectId handle.

pymor.tools.mpi.method_call(obj_id, name_, *args, **kwargs)

Execute a method with given arguments.

Intended to be used in conjunction with call. Arguments of type ObjectId are transparently mapped to the object they refer to.

Parameters:

• obj_id – The ObjectId of the object on which to call the method.

• name_ – Name of the method to call.

• args – Positional arguments for the method.

• kwargs – Keyword arguments for the method.

pymor.tools.mpi.method_call_manage(obj_id, name_, *args, **kwargs)

Execute a method with given arguments and manage the return value.

Intended to be used in conjunction with call. The return value of the called method is managed by calling manage_object and the corresponding ObjectId is returned. Arguments of type ObjectId are transparently mapped to the object they refer to.

Parameters:

• obj_id – The ObjectId of the object on which to call the method.

• name_ – Name of the method to call.

• args – Positional arguments for the method.

• kwargs – Keyword arguments for the method.

pymor.tools.mpi.mpi_info()

Print some information on the MPI setup.

Intended to be used in conjunction with call.

pymor.tools.mpi.quit()

Exit the event loop on all MPI ranks.

This will cause event_loop to terminate on all MPI ranks.

pymor.tools.mpi.remove_object(obj_id)

Remove the object referred to by obj_id from the registry.

pymor.tools.mpi.run_code(code)

Execute the code string code.

Intended to be used in conjunction with call.

pymor.tools.mpi.comm

pymor.tools.mpi.filename

pymor.tools.mpi.parallel

pymor.tools.mpi.rank0