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Use spawn start method in multiprocessing programs #11391

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XuehaiPan
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@XuehaiPan XuehaiPan commented May 2, 2024

Describe your change:

Set the start method to spawn before any multiprocess context is read.

Resolves: #769 (comment)

cc @cclauss

  • Add an algorithm?
  • Fix a bug or typo in an existing algorithm?
  • Add or change doctests? -- Note: Please avoid changing both code and tests in a single pull request.
  • Documentation change?

Checklist:

  • I have read CONTRIBUTING.md.
  • This pull request is all my own work -- I have not plagiarized.
  • I know that pull requests will not be merged if they fail the automated tests.
  • This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
  • All new Python files are placed inside an existing directory.
  • All filenames are in all lowercase characters with no spaces or dashes.
  • All functions and variable names follow Python naming conventions.
  • All function parameters and return values are annotated with Python type hints.
  • All functions have doctests that pass the automated testing.
  • All new algorithms include at least one URL that points to Wikipedia or another similar explanation.
  • If this pull request resolves one or more open issues then the description above includes the issue number(s) with a closing keyword: "Fixes #ISSUE-NUMBER".

process_array_.append(
Process(
multiprocessing_context.Process(
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@XuehaiPan XuehaiPan May 2, 2024

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I add a commit to access the multiprocessing context explicitly. The context instance is set to spawn above separating from the global default context.

import multiprocessing as mp

mp.set_start_method("spawn")  # set global default context

# Use the global default context
process = mp.Process(...)
pipe = mp.Pipe(...)
lock = mp.Lock(...)

vs.

import multiprocessing as mp

ctx = mp.get_context("spawn")

# Use the spawn context explicitly
process = ctx.Process(...)
pipe = ctx.Pipe(...)
lock = ctx.Lock(...)

If this change is not desired or makes the code too complex, I can remove the last commit in the PR. cc @cclauss

@cclauss cclauss merged commit ea53051 into TheAlgorithms:master May 2, 2024
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cclauss commented May 2, 2024

AWESOME!!

@XuehaiPan XuehaiPan deleted the multiprocessing-start-method branch May 2, 2024 16:48
sedatguzelsemme pushed a commit to sedatguzelsemme/Python that referenced this pull request Sep 15, 2024
…1391)

* Use `spawn` start method in multiprocessing programs

* Set `spawn` start method in doctest

* Use `with` statement for locks

* Pass multiprocessing context explicitly
@isidroas isidroas mentioned this pull request Jan 25, 2025
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2 participants