Building wheel taking an extremely long time

[charliehoward]

Expected behaviour

For it to install quickly.

Actual behaviour

If you run pip3 install opencv-python the installation appears to get stuck at Building wheel for opencv-python. I left it for about an hour with no visible progress.
I've since run pip3 install opencv-python --verbose and as of writing I'm an hour in at 28%.

Steps to reproduce

• See above
• Raspberry Pi OS Bullseye
• ARM
• 4.8.1.78

Issue submission checklist

• This is not a generic OpenCV usage question (looking for help for coding, other usage questions, homework etc.)
• I have read the README of this repository and understand that this repository provides only an automated build toolchain for OpenCV Python packages (there is no actual OpenCV code here)
• The issue is related to the build scripts in this repository, to the pre-built binaries or is a feature request (such as "please enable this additional dependency")
• I'm using the latest version of opencv-python

[charliehoward]

It's been about 3/4 hours now and it's at 100% but it's been stuck on [100%] Building CXX object modules/python3/CMakeFiles/opencv_python3.dir/__/src2/cv2.cpp.o for about 20 minutes, think I'm going to give up. Any ideas on a fix?

[skvark]

It takes several hours to build OpenCV on RPi. Nothing unusual there.

[charliehoward]

Yeah not 10+

[Only1leddy]

Im trying to compile opencv on a pi zero, iv done it with a very lite setup before, it took 8hours but worked, if youn think it's crash just leave it takes AGES so now im trying to use a setup for ml and object detection. So currently it been compiling for 24hours and is at 34percent 👐🧘‍♂️ so im looking at a few more days 😅 strap in

[twelho]

Try running export CMAKE_BUILD_PARALLEL_LEVEL=$(nproc) before pip install opencv-python. This makes the cmake --build invocation of opencv-python use all cores, and enabled me to build it in minutes instead of hours.