Source code for lightning.fabric.plugins.environments.mpi

# Copyright The Lightning AI team.
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# See the License for the specific language governing permissions and
# limitations under the License.

import logging
import socket
from functools import lru_cache
from typing import Optional

from lightning_utilities.core.imports import RequirementCache
from typing_extensions import override

from lightning.fabric.plugins.environments.cluster_environment import ClusterEnvironment
from lightning.fabric.plugins.environments.lightning import find_free_network_port

log = logging.getLogger(__name__)

_MPI4PY_AVAILABLE = RequirementCache("mpi4py")

[docs]class MPIEnvironment(ClusterEnvironment): """An environment for running on clusters with processes created through MPI. Requires the installation of the `mpi4py` package. See also: """ def __init__(self) -> None: if not _MPI4PY_AVAILABLE: raise ModuleNotFoundError(str(_MPI4PY_AVAILABLE)) from mpi4py import MPI self._comm_world = MPI.COMM_WORLD self._comm_local: Optional[MPI.Comm] = None self._node_rank: Optional[int] = None self._main_address: Optional[str] = None self._main_port: Optional[int] = None @property @override def creates_processes_externally(self) -> bool: return True @property @override def main_address(self) -> str: if self._main_address is None: self._main_address = self._get_main_address() return self._main_address @property @override def main_port(self) -> int: if self._main_port is None: self._main_port = self._get_main_port() return self._main_port
[docs] @staticmethod @override def detect() -> bool: """Returns ``True`` if the `mpi4py` package is installed and MPI returns a world size greater than 1.""" if not _MPI4PY_AVAILABLE: return False from mpi4py import MPI return MPI.COMM_WORLD.Get_size() > 1
[docs] @override @lru_cache(1) def world_size(self) -> int: return self._comm_world.Get_size()
@override def set_world_size(self, size: int) -> None: log.debug("MPIEnvironment.set_world_size was called, but setting world size is not allowed. Ignored.")
[docs] @override @lru_cache(1) def global_rank(self) -> int: return self._comm_world.Get_rank()
@override def set_global_rank(self, rank: int) -> None: log.debug("MPIEnvironment.set_global_rank was called, but setting global rank is not allowed. Ignored.")
[docs] @override @lru_cache(1) def local_rank(self) -> int: if self._comm_local is None: self._init_comm_local() assert self._comm_local is not None return self._comm_local.Get_rank()
[docs] @override def node_rank(self) -> int: if self._node_rank is None: self._init_comm_local() assert self._node_rank is not None return self._node_rank
def _get_main_address(self) -> str: return self._comm_world.bcast(socket.gethostname(), root=0) def _get_main_port(self) -> int: return self._comm_world.bcast(find_free_network_port(), root=0) def _init_comm_local(self) -> None: hostname = socket.gethostname() all_hostnames = self._comm_world.gather(hostname, root=0) # returns None on non-root ranks # sort all the hostnames, and find unique ones unique_hosts = sorted(set(all_hostnames)) if all_hostnames is not None else [] unique_hosts = self._comm_world.bcast(unique_hosts, root=0) # find the index for this host in the list of hosts: self._node_rank = unique_hosts.index(hostname) self._comm_local = self._comm_world.Split(color=self._node_rank)