# Bumps documentation

## mapper - Parallel processing implementations

`BaseMapper` |
`MPIMapper` |
`MPMapper` |
`SerialMapper` |
`can_pickle` | Returns True if problem can be pickled.
`nice` |
`setpriority` | Set The Priority of a Windows Process.
`using_mpi` |

Parallel and serial mapper implementations.

The API is a bit crufty since interprocess communication has evolved from the original implementation. And the names are misleading.

Usage:

    Mapper.start_worker(problem)
    mapper = Mapper.start_mapper(problem, None, cpus)
    result = mapper(points)
    ...
    mapper = Mapper.start_mapper(problem, None, cpus)
    result = mapper(points)
    Mapper.stop_mapper()

class bumps.mapper.BaseMapper

  Bases: `object`

  has_problem = False
  static start_mapper(problem, modelargs=None, cpus=0)

    Called with the problem on a new fit.

  static start_worker(problem)

    Called with the problem to initialize the worker

  static stop_mapper(mapper=None)

class bumps.mapper.MPIMapper

  Bases: `BaseMapper`

  has_problem = True

    For MPIMapper only the worker is initialized with the fit problem.

  static start_mapper(problem, modelargs=None, cpus=0)

    Called with the problem on a new fit.

  static start_worker(problem)

    Start the worker process.

    For the main process this does nothing and returns immediately. The worker processes never return.

    Each worker sits in a loop waiting for the next batch of points for the problem, or for the next problem. Set t problem is set to None, then exit the process and never

  static stop_mapper(mapper=None)

class bumps.mapper.MPMapper

  Bases: `BaseMapper`

  has_problem = False
  manager = None
  pool = None
  problem = None
  problem_id = 0
  shared_pickled_problem = None
  static start_mapper(problem, modelargs=None, cpus=0)

    Called with the problem on a new fit.

  static start_worker(problem)

    Called with the problem to initialize the worker

  static stop_mapper(mapper=None)

class bumps.mapper.SerialMapper

  Bases: `BaseMapper`

  has_problem = False
  static start_mapper(problem, modelargs=None, cpus=0)

    Called with the problem on a new fit.

  static start_worker(problem)

    Called with the problem to initialize the worker

  static stop_mapper(mapper=None)

bumps.mapper.can_pickle(problem, check=False)

  Returns True if problem can be pickled.

  If this method returns False then MPMapper cannot be used and SerialMapper should be used instead.

  If check is True then call nllf() on the duplicated object as a “smoke test” to verify that the function will run after copying. This is not foolproof. For example, access to a database may work in the duplicated object because the connection is open and available in the current process, but it will fail when trying to run on a remote machine.

bumps.mapper.nice()

bumps.mapper.setpriority(pid=None, priority=1)

  Set The Priority of a Windows Process. Priority is a value between 0-5 where 2 is normal priority and 5 is maximum. Default sets the priority of the current python process but can take any valid process ID.

bumps.mapper.using_mpi()