pybnb.mpi_utils

Various utility function for MPI.

Copyright by Gabriel A. Hackebeil (gabe.hackebeil@gmail.com).

class pybnb.mpi_utils.Message(comm)[source]

A helper class for probing for and receiving messages. A single instance of this class is meant to be reused.

Parameters:comm (mpi4py.MPI.Comm) – The MPI communicator to use.
probe(**kwds)[source]

Perform a blocking test for a message

recv(datatype=None, data=None)[source]

Complete the receive for the most recent message probe and return the data as a numeric array or a string, depending on the datatype keyword.

Parameters:
  • datatype ({mpi4py.MPI.DOUBLE, mpi4py.MPI.CHAR}, optional) – An MPI datatype used to interpret the received data. If None, mpi4py.MPI.DOUBLE will be used. (default: None)
  • data (array.array or None, optional) – An existing data array to store data into. If None, one will be created. (default: None)
pybnb.mpi_utils.recv_nothing(comm, status)[source]

A helper function for receiving an empty message. This function is not thread safe.

Parameters:
  • comm (mpi4py.MPI.Comm) – An MPI communicator.
  • status (mpi4py.MPI.Status) – An MPI status object that has been populated with information about the message to be received via a probe. If None, a new status object will be created and an empty message will be expected from any source with any tag. (default: None)
Returns:

status – If the original status argument was not None, it will be returned after being updated by the receive. Otherwise, the status object that was created will be returned.
Return type:

mpi4py.MPI.Status
pybnb.mpi_utils.send_nothing(comm, dest, tag=0)[source]

A helper function for sending an empty message with a given tag. This function is not thread safe.

Parameters:
  • comm (mpi4py.MPI.Comm) – An MPI communicator.
  • dest (int) – The process rank to send the message to.
  • tag (int, optional) – A valid MPI tag to use for the message. (default: 0)
pybnb.mpi_utils.recv_data(comm, status, datatype, out=None)[source]

A helper function for receiving numeric or string data sent using the lower-level buffer-based mpi4py routines.

Parameters:
  • comm (mpi4py.MPI.Comm) – An MPI communicator.
  • status (mpi4py.MPI.Status) – An MPI status object that has been populated with information about the message to be received via a probe.
  • datatype (mpi4py.MPI.Datatype) – An MPI datatype used to interpret the received data. If the datatype is mpi4py.MPI.CHAR, the received data will be converted to a string.
  • out (buffer-like object, optional) – A buffer-like object that is compatible with the datatype argument and can be passed to comm.Recv. Can only be left as None when the datatype is mpi4py.MPI.CHAR.
Returns:
Return type:

string or user-provided data buffer