Removing task kills background process when bound

Question

Background

I have an app that uses two processes:

• UI
• Background

The background process hosts two services:

• A long-running foreground service (started with startService and made foreground using startForeground), ImportantService. It uses START_STICKY to ensure it isn't killed if
• A temporary one for inter-process communication, SettingsService.

The UI binds to the temporary service in the background process for inter-process communication using bindService(..., ..., Context.BIND_AUTO_CREATE).

Problem

If I open the Recents activity on my phone and swipe to kill/remove my activity after it has bound to SettingsService, the entire background process is killed, and ImportantService is consequently killed.

Symptoms

• ImportantService is restarted after being killed, probably due to START_STICKY.
• This doesn't happen if the services are moved into the UI process.
• This doesn't happen if I start SettingsService via startService() but don't bind to it. The problem seems to be triggered by binding to the service.

What I've Tried

• Starting SettingsService using startService() before binding to it using bindService().
• Using each of the available flags for bindService().
• Unbinding from SettingsService in onPause(). This prevents the problem from happening the first time, but it still happens on subsequent tests.
• Making SettingsService bind to itself.

Environment

• Device: Sony Xperia M
• OS: Android 5.1.1
• Customisation: Cyanogenmod 12.1
• Also reproduced the problem in Genymotion emulator running Android 4.4.4

Logcat Main Buffer Logs

06-17 07:27:22.633      678-897/? I/ActivityManager﹕ Killing 7666:com.example.myapp/u0a151 (adj 9): remove task
06-17 07:27:22.650     678-1327/? I/WindowState﹕ WIN DEATH: Window{3e26d1c9 u0 com.example.myapp/.SettingsActivity}
06-17 07:27:22.769     678-1211/? I/ActivityManager﹕ Killing 32110:com.example.myapp:backgroundprocess/u0a151 (adj 0): remove task
06-17 07:27:22.898     678-1149/? W/ActivityManager﹕ Scheduling restart of crashed service com.example.myapp/.ImportantService in 1000ms
06-17 07:27:23.979      678-696/? I/ActivityManager﹕ Start proc 7809:com.example.myapp:backgroundprocess/u0a151 for service com.example.myapp/.ImportantService

Logcat Event Buffer Logs

06-17 20:33:08.482 I/am_finish_activity(  678): [0,395523242,1024,com.example.myapp/.SettingsActivity,clear]
06-17 20:33:08.484 I/am_destroy_activity(  678): [0,395523242,1024,com.example.myapp/.SettingsActivity,finish-imm]
06-17 20:33:08.488 I/am_kill (  678): [0,5636,com.example.myapp,9,remove task]
06-17 20:33:08.640 I/dvm_lock_sample(  678): [system_server,1,ActivityManager,142,ActivityManagerService.java,3410,-,8682,28]
06-17 20:33:08.644 I/am_proc_died(  678): [0,5636,com.example.myapp]
06-17 20:33:08.645 I/am_kill (  678): [0,3960,com.example.myapp:backgroundprocess,0,remove task]
06-17 20:33:08.811 I/wm_task_removed(  678): [1024,removeAppToken: last token]
06-17 20:33:08.812 I/wm_task_removed(  678): [1024,removeTask]
06-17 20:33:08.816 I/dvm_lock_sample(  678): [system_server,1,Binder_F,136,ActivityManagerService.java,1230,-,1230,27]
06-17 20:33:08.819 I/am_proc_died(  678): [0,3960,com.example.myapp:backgroundprocess]

Answer 1

This seems to be an Android bug. I've filed an issue for it at:

Issue 178057: Process killed when task removed while bound to service with BIND_AUTO_CREATE flag.

Here are some workarounds taken from the above:

1. In the foreground service's onTaskRemoved(), launch an activity on task removal
   • Fixes the problem about 75% of the time.
   • This closes the "Recents" activity on the user, so it alters the normal task-closing experience for the user.
   • Seems to depend on timing, so it mightn't be a perfect workaround
2. In the foreground service's onTaskRemoved(), send multiple broadcasts to a registered receiver in the application with the Intent.FLAG_RECEIVER_FOREGROUND flag.
   • Seems to nearly always work, depending on timing and the number of broadcasts you send
3. Unbind from the background service before the task is removed