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docs: add multiprocessing fork safety warning (fixes #1166) #1225

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docs: add multiprocessing fork safety warning (fixes #1166) #1225

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19a9c9b
fix: add explicit NumPy version constraints for Python 3.13+ and 3.14
molhamfetnah May 9, 2026
4e4505a
docs: add multiprocessing fork safety warning
molhamfetnah May 9, 2026
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21 changes: 20 additions & 1 deletion scripts/__init__.py
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Original file line number Diff line number Diff line change
@@ -1,3 +1,22 @@
"""
OpenCV Python bindings

This module provides Python bindings for OpenCV.

Important notes for multiprocessing:
- OpenCV is not fork-safe. Using cv2 functions after fork() can cause
"corrupted double-linked list" errors and memory corruption.
- If you use multiprocessing with fork (the default on Linux/macOS),
either:
1. Use spawn mode: multiprocessing.set_start_method('spawn')
2. Call cv2.setNumThreads(0) in each worker before using cv2
- See: https://github.com/opencv/opencv-python/issues/1166
"""

import os
import sys
import warnings

PYTHON_EXTENSIONS_PATHS = [
LOADER_DIR
] + PYTHON_EXTENSIONS_PATHS
Expand All @@ -21,4 +40,4 @@
if sys.platform.startswith("linux") and ci_and_not_headless:
os.environ["QT_QPA_FONTDIR"] = os.path.join(
os.path.dirname(os.path.abspath(__file__)), "qt", "fonts"
)
)
4 changes: 3 additions & 1 deletion setup.py
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Expand Up @@ -24,7 +24,9 @@ def main():

install_requires = [
'numpy<2.0; python_version<"3.9"',
'numpy>=2; python_version>="3.9"',
'numpy>=2.0.2; python_version>="3.9" and python_version<"3.13"',
'numpy>=2.1.3; python_version>="3.13" and python_version<"3.14"',
'numpy>=2.3.0; python_version>="3.14"',
]

python_version = cmaker.CMaker.get_python_version()
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