from .._network import Network
from .._parameters import Parameters
from .._outputfiles import OutputFiles
import os
import sys
from contextlib import contextmanager
__all__ = ["run_worker", "prepare_worker"]
global_network = None
@contextmanager
def silence_output():
"""Nice way to silence stdout and stderr - thanks to
Emil Stenström in
https://stackoverflow.com/questions/6735917/redirecting-stdout-to-nothing-in-python
"""
new_out = open(os.devnull, "w")
old_out = sys.stdout
sys.stdout = new_out
new_err = open(os.devnull, "w")
old_err = sys.stderr
sys.stderr = new_err
try:
yield new_out
finally:
sys.stdout = old_out
sys.stderr = old_err
[docs]def prepare_worker(params: Parameters):
"""Prepare a worker to receive work to run a model using the passed
parameters. This will build the network specified by the
parameters and will store it in global memory ready to
be used for a model run. Note that these are
silent, printing nothing to stdout or stderr
"""
# switch off printing to stdout and stderr
with silence_output():
global global_network
if global_network is None:
global_network = Network.build(params=params,
calculate_distances=True,
profile=False)
else:
global_network.update(params)
def run_worker(arguments):
"""Ask the worker to run a model using the passed variables and
options. This will write to options['output_dir'] and will
also return the population object that contains the final
population data.
WARNING - the iterator and extractor arguments rely on the
workers starting in the same directory as the main process,
so that they can load the same python files (if the user
is using a custom iterator or extractor)
"""
params = arguments["params"]
options = arguments["options"]
# first, build and prepare the network
prepare_worker(params)
# next, run the job, writing to output
from ._runner import redirect_output
outdir = options["output_dir"]
auto_bzip = options["auto_bzip"]
del options["auto_bzip"]
# if the user wanted to remove this directory then they would
# have done so in the main process - no need to check again
with OutputFiles(outdir, check_empty=False, force_empty=False,
prompt=None, auto_bzip=auto_bzip) as output_dir:
options["output_dir"] = output_dir
with redirect_output(output_dir.get_path()):
global global_network
output = global_network.run(**options)
return output