_multiprocessing

[sm-jalali-f]

i developed app that user keras library for deep learning.
when run app with buildozer this error occured:
11-16 15:13:08.008 5607 5924 I python : Traceback (most recent call last): 11-16 15:13:08.008 5607 5924 I python : File "/home/mohamad/projects/andcai/readKontor/.buildozer/android/app/main.py", line 6, in <module> 11-16 15:13:08.008 5607 5924 I python : File "/home/mohamad/projects/andcai/readKontor/.buildozer/android/app/digit_detector/classify.py", line 4, in <module> 11-16 15:13:08.009 5607 5924 I python : File "/home/mohamad/projects/andcai/readKontor/.buildozer/android/platform/build/dists/myapp/private/lib/python2.7/site-packages/keras/__init__.py", line 3, in <module> 11-16 15:13:08.009 5607 5924 I python : File "/home/mohamad/projects/andcai/readKontor/.buildozer/android/platform/build/dists/myapp/private/lib/python2.7/site-packages/keras/utils/__init__.py", line 4, in <module> 11-16 15:13:08.009 5607 5924 I python : File "/home/mohamad/projects/andcai/readKontor/.buildozer/android/platform/build/dists/myapp/private/lib/python2.7/site-packages/keras/utils/data_utils.py", line 6, in <module> 11-16 15:13:08.010 5607 5924 I python : File "/home/mohamad/projects/andcai/readKontor/.buildozer/android/platform/build/build/other_builds/python2/armeabi-v7a/python2/python-install/lib/python2.7/multiprocessing/__init__.py", line 84, in <module> 11-16 15:13:08.010 5607 5924 I python : ImportError: No module named _multiprocessing 11-16 15:13:08.043 5607 5924 I python : Python for android ended.

[inclement]

I think our python build just doesn't support multiprocessing on Android. I think there was a technical reason for this, but I don't remember the details.

[inclement]

I asked @tshirtman, and he confirmed that multiprocessing is originally missing for technical reasons. There is a little information about it here.

It's possible that multiprocessing could be made to work now, given how much Android has changed over the years, but I don't know what would be involved.

[zanadu123]

i encounter similar issue when using multiprocessing. when i run app on android, the logcat says:

10-24 21:31:38.558 14600 14649 I python  :  ImportError: cannot import name 'sem_unlink' from '_multiprocessing' (/data/user/0/znd.ccc.cfst/files/app/_python_bundle/modules/_multiprocessing.cpython-37m.so)

and

10-24 21:31:38.588 14600 14649 I python  :    File "/client/.buildozer/android/platform/build/build/other_builds/python3-libffi-openssl-sqlite3/armeabi-v7a__ndk_target_21/python3/Lib/multiprocessing/synchronize.py", line 32, in <module>
10-24 21:31:38.588 14600 14649 I python  :  ImportError: This platform lacks a functioning sem_open implementation, therefore, the required synchronization primitives needed will not function, see issue 3770.

my phone is vivo Y55, android 6.0.1. buildozer version is 0.39