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How can I configure multiprocessing in Windows to use the 'forkserver' method? whenever I start up IPython console and type:
import multiprocessing
multiprocessing.set_start_method('forkserver')
the error:
ValueError: cannot find context for 'forkserver'
occurs.
452
asked Sep 03 '17 08:09
You should not use the multiprocessing package in a Numba code. This will simply not work (Numba will use a fallback implementation which is the basic Python one).
Passing Keyword Arguments to Multiprocessing Processes We can also pass in arguments corresponding to the parameter name using the kwargs parameter in the Process class. Instead of passing a tuple, we pass a dictionary to kwargs where we specify the argument name and the variable being passed in as that argument.
You can share a global variable with all child workers processes in the multiprocessing pool by defining it in the worker process initialization function. In this tutorial you will discover how to share global variables with all workers in the Python process pool.
Passing Messages to Processes A simple way to communicate between process with multiprocessing is to use a Queue to pass messages back and forth. Any pickle-able object can pass through a Queue. This short example only passes a single message to a single worker, then the main process waits for the worker to finish.
forkserver is only available in Python 3.4+ and only on some Unix platforms (not on Windows).
From the documentation:
forkserverAvailable on Unix platforms which support passing file descriptors over Unix pipes.
Changed in version 3.4: [...]
forkserveradded for some unix platforms.
The reason forkserver is not available on Windows is that it relies on fork(), and there is no fork() on Windows. For more information, see How can I start a sub-process in Windows?
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