App restart via the UI causes an error

[rtibbles]

Observed behavior

When trying to toggle device settings that require a restart (such as enabled plugins), the app crashes.

Errors and logs

2023-10-09 10:55:53.821  5845-5917  python                  org.learningequality.Kolibri         I  INFO     2023-10-09 17:55:53,816 127.0.0.1 - - "POST /api/device/devicerestart/" 200 0 "http://127.0.0.1:57967/en/device/" "Mozilla/5.0 (Linux; Android 7.1.1; Android SDK built for x86 Build/NYC; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/55.0.2883.91 Mobile Safari/537.36"
2023-10-09 10:55:53.924  5845-5914  python                  org.learningequality.Kolibri         I  INFO     2023-10-09 17:55:53,923 Restarting server.
2023-10-09 10:55:53.925  5845-5914  python                  org.learningequality.Kolibri         I  INFO     2023-10-09 17:55:53,924 Bus state: STOP
2023-10-09 10:55:54.038  5845-5845  art                     org.learningequality.Kolibri         W  Attempt to remove non-JNI local reference, dumping thread
2023-10-09 10:55:54.071  5845-5914  python                  org.learningequality.Kolibri         I  INFO     2023-10-09 17:55:54,071 HTTP Server kolibri.utils.server.Server(('0.0.0.0', 55884)) shut down
2023-10-09 10:55:54.313  5845-5914  python                  org.learningequality.Kolibri         I  INFO     2023-10-09 17:55:54,312 HTTP Server kolibri.utils.server.Server(('0.0.0.0', 57967)) shut down
2023-10-09 10:55:54.313  5845-5914  python                  org.learningequality.Kolibri         I  INFO     2023-10-09 17:55:54,313 Joining 'ZeroConfPlugin'
2023-10-09 10:55:54.315  5845-5845  art                     org.learningequality.Kolibri         W  Attempt to remove non-JNI local reference, dumping thread
2023-10-09 10:55:54.600  5845-5845  art                     org.learningequality.Kolibri         W  Attempt to remove non-JNI local reference, dumping thread
2023-10-09 10:55:54.929  5845-5845  art                     org.learningequality.Kolibri         W  Attempt to remove non-JNI local reference, dumping thread
2023-10-09 10:55:54.942  5845-5914  python                  org.learningequality.Kolibri         I  INFO     2023-10-09 17:55:54,941 Stopped thread 'ZeroConfPlugin'.
2023-10-09 10:55:54.948  5845-5856  art                     org.learningequality.Kolibri         I  Background sticky concurrent mark sweep GC freed 7(328B) AllocSpace objects, 0(0B) LOS objects, 0% free, 27MB/27MB, paused 6.699ms total 11.667ms
2023-10-09 10:55:54.995  5845-5914  TaskworkerWorker        org.learningequality.Kolibri         V  Request data: Data {LONG_RUNNING_ARGUMENT : false, PYTHON_WORKER_ARGUMENT : 1000, androidx.work.impl.workers.RemoteListenableWorker.ARGUMENT_CLASS_NAME : org.learningequality.Kolibri.TaskworkerWorkerService, androidx.work.impl.workers.RemoteListenableWorker.ARGUMENT_PACKAGE_NAME : org.learningequality.Kolibri, }
2023-10-09 10:55:55.252  5845-5845  art                     org.learningequality.Kolibri         W  Attempt to remove non-JNI local reference, dumping thread
2023-10-09 10:55:55.264  5845-5914  python                  org.learningequality.Kolibri         I  INFO     2023-10-09 17:55:55,263 Bus state: IDLE
2023-10-09 10:55:55.265  5845-5914  python                  org.learningequality.Kolibri         I  INFO     2023-10-09 17:55:55,264 Bus state: EXIT
2023-10-09 10:55:55.267  5845-5914  python                  org.learningequality.Kolibri         I  INFO     2023-10-09 17:55:55,266 Waiting for child threads to terminate...
2023-10-09 10:55:55.268  5845-5914  python                  org.learningequality.Kolibri         I  INFO     2023-10-09 17:55:55,267 Bus state: EXITED
2023-10-09 10:55:55.269  5845-5914  python                  org.learningequality.Kolibri         I  INFO     2023-10-09 17:55:55,268 Re-spawning notaninterpreterreally
2023-10-09 10:55:55.278  5845-5890  python                  org.learningequality.Kolibri         I  INFO     2023-10-09 17:55:55,268 Re-spawning notaninterpreterreally
2023-10-09 10:55:55.355  5845-5890  python                  org.learningequality.Kolibri         I  ERROR    2023-10-09 17:55:55,288 Error in 'execv' listener <bound method Execv.execv of <magicbus.plugins.lifecycle.Execv object at 0x8df48058>>
2023-10-09 10:55:55.355  5845-5890  python                  org.learningequality.Kolibri         I  Traceback (most recent call last):
2023-10-09 10:55:55.355  5845-5890  python                  org.learningequality.Kolibri         I    File "/home/richard/github/kolibri-installer-android/python-for-android/build/python-installs/kolibri/x86/kolibri/dist/magicbus/base.py", line 273, in publish
2023-10-09 10:55:55.355  5845-5890  python                  org.learningequality.Kolibri         I    File "/home/richard/github/kolibri-installer-android/python-for-android/build/python-installs/kolibri/x86/kolibri/dist/magicbus/plugins/lifecycle.py", line 92, in execv
2023-10-09 10:55:55.355  5845-5890  python                  org.learningequality.Kolibri         I  ValueError: execv() arg 2 first element cannot be empty
2023-10-09 10:55:55.355  5845-5890  python                  org.learningequality.Kolibri         I  
2023-10-09 10:55:55.355  5845-5890  python                  org.learningequality.Kolibri         I  Traceback (most recent call last):
2023-10-09 10:55:55.355  5845-5890  python                  org.learningequality.Kolibri         I    File "/home/richard/github/kolibri-installer-android/src/main.py", line 83, in <module>
2023-10-09 10:55:55.356  5845-5890  python                  org.learningequality.Kolibri         I    File "/home/richard/github/kolibri-installer-android/python-for-android/build/python-installs/kolibri/x86/kolibri/utils/server.py", line 739, in run
2023-10-09 10:55:55.356  5845-5890  python                  org.learningequality.Kolibri         I    File "/home/richard/github/kolibri-installer-android/python-for-android/build/python-installs/kolibri/x86/kolibri/dist/magicbus/process.py", line 156, in block
2023-10-09 10:55:55.356  5845-5890  python                  org.learningequality.Kolibri         I    File "/home/richard/github/kolibri-installer-android/python-for-android/build/python-installs/kolibri/x86/kolibri/dist/magicbus/base.py", line 291, in publish
2023-10-09 10:55:55.356  5845-5890  python                  org.learningequality.Kolibri         I  magicbus.base.ChannelFailures: ValueError('execv() arg 2 first element cannot be empty')
2023-10-09 10:55:55.356  5845-5890  python                  org.learningequality.Kolibri         I  Python for android ended.
2023-10-09 10:55:55.362  5845-5914  python                  org.learningequality.Kolibri         I  ERROR    2023-10-09 17:55:55,300 Error in 'EXITED' listener <bound method Execv.execv of <magicbus.plugins.lifecycle.Execv object at 0x8df48058>>
2023-10-09 10:55:55.362  5845-5914  python                  org.learningequality.Kolibri         I  Traceback (most recent call last):
2023-10-09 10:55:55.362  5845-5914  python                  org.learningequality.Kolibri         I    File "/home/richard/github/kolibri-installer-android/python-for-android/build/python-installs/kolibri/x86/kolibri/dist/magicbus/base.py", line 273, in publish
2023-10-09 10:55:55.362  5845-5914  python                  org.learningequality.Kolibri         I    File "/home/richard/github/kolibri-installer-android/python-for-android/build/python-installs/kolibri/x86/kolibri/dist/magicbus/plugins/lifecycle.py", line 92, in execv
2023-10-09 10:55:55.362  5845-5914  python                  org.learningequality.Kolibri         I  ValueError: execv() arg 2 first element cannot be empty
2023-10-09 10:55:55.362  5845-5914  python                  org.learningequality.Kolibri         I  
2023-10-09 10:55:55.374  5845-5914  python                  org.learningequality.Kolibri         I  ERROR    2023-10-09 17:55:55,362 Error in background task thread function <bound method ProcessControlPlugin.run of <kolibri.utils.server.ProcessControlPlugin object at 0x90068730>>.
2023-10-09 10:55:55.374  5845-5914  python                  org.learningequality.Kolibri         I  Traceback (most recent call last):
2023-10-09 10:55:55.374  5845-5914  python                  org.learningequality.Kolibri         I    File "/home/richard/github/kolibri-installer-android/python-for-android/build/python-installs/kolibri/x86/kolibri/dist/magicbus/plugins/tasks.py", line 90, in run
2023-10-09 10:55:55.374  5845-5914  python                  org.learningequality.Kolibri         I    File "/home/richard/github/kolibri-installer-android/python-for-android/build/python-installs/kolibri/x86/kolibri/utils/server.py", line 594, in run
2023-10-09 10:55:55.374  5845-5914  python                  org.learningequality.Kolibri         I    File "/home/richard/github/kolibri-installer-android/python-for-android/build/python-installs/kolibri/x86/kolibri/dist/magicbus/process.py", line 128, in restart
2023-10-09 10:55:55.374  5845-5914  python                  org.learningequality.Kolibri         I    File "/home/richard/github/kolibri-installer-android/python-for-android/build/python-installs/kolibri/x86/kolibri/dist/magicbus/base.py", line 186, in transition
2023-10-09 10:55:55.374  5845-5914  python                  org.learningequality.Kolibri         I    File "/home/richard/github/kolibri-installer-android/python-for-android/build/python-installs/kolibri/x86/kolibri/dist/magicbus/base.py", line 215, in _transition
2023-10-09 10:55:55.374  5845-5914  python                  org.learningequality.Kolibri         I    File "/home/richard/github/kolibri-installer-android/python-for-android/build/python-installs/kolibri/x86/kolibri/dist/magicbus/base.py", line 291, in publish
2023-10-09 10:55:55.374  5845-5914  python                  org.learningequality.Kolibri         I  magicbus.base.ChannelFailures: ValueError('execv() arg 2 first element cannot be empty')
2023-10-09 10:55:55.374  5845-5914  python                  org.learningequality.Kolibri         I  
2023-10-09 10:55:55.374  5845-5914  python                  org.learningequality.Kolibri         I  Exception in thread ProcessControlPlugin:
2023-10-09 10:55:55.374  5845-5914  python                  org.learningequality.Kolibri         I  Traceback (most recent call last):
2023-10-09 10:55:55.374  5845-5914  python                  org.learningequality.Kolibri         I    File "/home/richard/github/kolibri-installer-android/python-for-android/build/other_builds/python3/x86__ndk_target_23/python3/Lib/threading.py", line 980, in _bootstrap_inner
2023-10-09 10:55:55.375  5845-5914  python                  org.learningequality.Kolibri         I    File "/home/richard/github/kolibri-installer-android/python-for-android/build/python-installs/kolibri/x86/kolibri/dist/magicbus/plugins/tasks.py", line 90, in run
2023-10-09 10:55:55.375  5845-5914  python                  org.learningequality.Kolibri         I    File "/home/richard/github/kolibri-installer-android/python-for-android/build/python-installs/kolibri/x86/kolibri/utils/server.py", line 594, in run
2023-10-09 10:55:55.375  5845-5914  python                  org.learningequality.Kolibri         I    File "/home/richard/github/kolibri-installer-android/python-for-android/build/python-installs/kolibri/x86/kolibri/dist/magicbus/process.py", line 128, in restart
2023-10-09 10:55:55.375  5845-5914  python                  org.learningequality.Kolibri         I    File "/home/richard/github/kolibri-installer-android/python-for-android/build/python-installs/kolibri/x86/kolibri/dist/magicbus/base.py", line 186, in transition
2023-10-09 10:55:55.375  5845-5914  python                  org.learningequality.Kolibri         I    File "/home/richard/github/kolibri-installer-android/python-for-android/build/python-installs/kolibri/x86/kolibri/dist/magicbus/base.py", line 215, in _transition
2023-10-09 10:55:55.375  5845-5914  python                  org.learningequality.Kolibri         I    File "/home/richard/github/kolibri-installer-android/python-for-android/build/python-installs/kolibri/x86/kolibri/dist/magicbus/base.py", line 291, in publish
2023-10-09 10:55:55.375  5845-5914  python                  org.learningequality.Kolibri         I  magicbus.base.ChannelFailures: ValueError('execv() arg 2 first element cannot be empty')

Expected behavior

The App should properly restart the Python process.

This should be achieved by creating a custom restart hook function that will properly handle restarting the Python process on Android and then passing that as the restart hook via an environment variable.

User-facing consequences

Not able to update important settings such as the file system path.

Steps to reproduce

Update the available plugins.
Save changes.