Hao to support multiprocess Queue in Android

[onsunsl]

Versions

• Python: 3.8.1
• OS: Ubuntu
• Kivy: 1.11.1
• Cython: 0.29.20
• OpenJDK: 1.8

Description

I use Queue synchronize two process in the code, but there is an error when run in Android.
It works fine under Ubuntu and Windows.

# sub process
class ApiLogUploader(Process):

    def __init__(self, q):
        super(ApiLogUploader, self).__init__()
        self.q = q

# main process
from multiprocessing import Queue
api_log_uploader = ApiLogUploader(Queue())   # <----  raise a exception in here

• Error info:

This platform lacks a functioning sem_open implementation, therefore, the required synchronization primitives needed will not function, see issue 3770.

Is this a Python bug in Android?

Logs

Traceback (most recent call last):
  File "/home/kivy/test/.buildozer/android/platform/build-armeabi-v7a/build/other_builds/python3/armeabi-v7a__ndk_target_21/python3/Lib/multiprocessing/synchronize.py", line 28, in <module>
ImportError: cannot import name 'sem_unlink' from '_multiprocessing' (/data/user/0/org.kivy.cpos/files/app/_python_bundle/modules/_multiprocessing.cpython-38.so)

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/kivy/test/.buildozer/android/app/common/http_interface.py", line 12, in <module>
  File "/home/kivy/test/.buildozer/android/app/dataprocessing/__init__.py", line 4, in <module>
  File "/home/kivy/test/.buildozer/android/platform/build-armeabi-v7a/build/other_builds/python3/armeabi-v7a__ndk_target_21/python3/Lib/multiprocessing/context.py", line 103, in Queue
  File "/home/kivy/test/.buildozer/android/platform/build-armeabi-v7a/build/other_builds/python3/armeabi-v7a__ndk_target_21/python3/Lib/multiprocessing/queues.py", line 39, in __init__
  File "<frozen zipimport>", line 259, in load_module
  File "/home/kivy/test/.buildozer/android/platform/build-armeabi-v7a/build/other_builds/python3/armeabi-v7a__ndk_target_21/python3/Lib/multiprocessing/synchronize.py", line 30, in <module>
ImportError: This platform lacks a functioning sem_open implementation, therefore, the required synchronization primitives needed will not function, see issue 3770.

This platform lacks a functioning sem_open implementation, therefore, the required synchronization primitives needed will not function, see issue 3770.
5

[Julian-O]

Multiprocessing isn't supported by the Android OS. Look at Services instead.