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ENH: Add mp_context plugin arg for MultiProc #2778

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Nov 15, 2018
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ENH: Add mp_context plugin arg for MultiProc #2778

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20 changes: 14 additions & 6 deletions nipype/pipeline/plugins/multiproc.py
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Original file line number Diff line number Diff line change
Expand Up @@ -11,7 +11,7 @@

# Import packages
import os
from multiprocessing import cpu_count
import multiprocessing as mp
from concurrent.futures import ProcessPoolExecutor
from traceback import format_exception
import sys
Expand Down Expand Up @@ -95,7 +95,7 @@ class MultiProcPlugin(DistributedPluginBase):

Currently supported options are:

- non_daemon : boolean flag to execute as non-daemon processes
- non_daemon: boolean flag to execute as non-daemon processes
- n_procs: maximum number of threads to be executed in parallel
- memory_gb: maximum memory (in GB) that can be used at once.
- raise_insufficient: raise error if the requested resources for
Expand All @@ -104,8 +104,7 @@ class MultiProcPlugin(DistributedPluginBase):
- scheduler: sort jobs topologically (``'tsort'``, default value)
or prioritize jobs by, first, memory consumption and, second,
number of threads (``'mem_thread'`` option).
- maxtasksperchild: number of nodes to run on each process before
refreshing the worker (default: 10).
- mp_context: name of multiprocessing context to use

"""

Expand All @@ -121,7 +120,7 @@ def __init__(self, plugin_args=None):
self._cwd = os.getcwd()

# Read in options or set defaults.
self.processors = self.plugin_args.get('n_procs', cpu_count())
self.processors = self.plugin_args.get('n_procs', mp.cpu_count())
self.memory_gb = self.plugin_args.get(
'memory_gb', # Allocate 90% of system memory
get_system_total_memory_gb() * 0.9)
Expand All @@ -133,7 +132,16 @@ def __init__(self, plugin_args=None):
'mem_gb=%0.2f, cwd=%s)',
self.processors, self.memory_gb, self._cwd)

self.pool = ProcessPoolExecutor(max_workers=self.processors)
try:
mp_context = mp.context.get_context(
self.plugin_args.get('mp_context'))
self.pool = ProcessPoolExecutor(max_workers=self.processors,
initializer=os.chdir,
initargs=(self._cwd,),
mp_context=mp_context)
except (AttributeError, TypeError):
# Python < 3.7 does not support initialization or contexts
self.pool = ProcessPoolExecutor(max_workers=self.processors)

self._stats = None

Expand Down