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Python

"""Utility function to construct a loky.ReusableExecutor with custom pickler.
This module provides efficient ways of working with data stored in
shared memory with numpy.memmap arrays without inducing any memory
copy between the parent and child processes.
"""
# Author: Thomas Moreau <thomas.moreau.2010@gmail.com>
# Copyright: 2017, Thomas Moreau
# License: BSD 3 clause
import random
from .disk import delete_folder
from ._memmapping_reducer import get_memmapping_reducers
from .externals.loky.reusable_executor import get_reusable_executor
_executor_args = None
def get_memmapping_executor(n_jobs, timeout=300, initializer=None, initargs=(),
env=None, **backend_args):
"""Factory for ReusableExecutor with automatic memmapping for large numpy
arrays.
"""
global _executor_args
# Check if we can reuse the executor here instead of deferring the test to
# loky as the reducers are objects that changes at each call.
executor_args = backend_args.copy()
executor_args.update(env if env else {})
executor_args.update(dict(
timeout=timeout, initializer=initializer, initargs=initargs))
reuse = _executor_args is None or _executor_args == executor_args
_executor_args = executor_args
id_executor = random.randint(0, int(1e10))
job_reducers, result_reducers, temp_folder = get_memmapping_reducers(
id_executor, **backend_args)
_executor = get_reusable_executor(n_jobs, job_reducers=job_reducers,
result_reducers=result_reducers,
reuse=reuse, timeout=timeout,
initializer=initializer,
initargs=initargs, env=env)
# If executor doesn't have a _temp_folder, it means it is a new executor
# and the reducers have been used. Else, the previous reducers are used
# and we should not change this attibute.
if not hasattr(_executor, "_temp_folder"):
_executor._temp_folder = temp_folder
else:
delete_folder(temp_folder)
return _executor
class _TestingMemmappingExecutor():
"""Wrapper around ReusableExecutor to ease memmapping testing with Pool
and Executor. This is only for testing purposes.
"""
def __init__(self, n_jobs, **backend_args):
self._executor = get_memmapping_executor(n_jobs, **backend_args)
self._temp_folder = self._executor._temp_folder
def apply_async(self, func, args):
"""Schedule a func to be run"""
future = self._executor.submit(func, *args)
future.get = future.result
return future
def terminate(self):
self._executor.shutdown()
delete_folder(self._temp_folder)
def map(self, f, *args):
res = self._executor.map(f, *args)
return list(res)