The ps command shows many repeating processes named "app_process". Why?

Question

as of today my phone (Samsung Galaxy Nexus (4.1.1) slows down a lot. I noticed following:

root@android:/ # ps | grep -c app_process                                      
136
root@android:/ # 

and here is few details:

root@android:/ # ps | grep app_process | tail                                  
root      3651  1     429424 12600 ffffffff 40061c74 S app_process
root      3667  1     429420 12596 ffffffff 400e3c74 S app_process
root      3680  1     429420 12596 ffffffff 4013cc74 S app_process
root      3681  1     429416 12596 ffffffff 4003bc74 S app_process
root      3682  1     429432 12608 ffffffff 400b4c74 S app_process
root      3711  3710  429424 12600 ffffffff 40102c74 S app_process
root      3722  3721  429424 15244 ffffffff 4004fc74 S app_process
root      3726  3725  429416 15236 ffffffff 40049c74 S app_process
root      3727  3723  429420 15240 ffffffff 4004ac74 S app_process
root      3728  3724  429420 15240 ffffffff 40014c74 S app_process
root@android:/ # 

I just boot my phone run adb logcat on my laptop and it's been 15 min already and screen already off yet I still see something going on through logcat. Is this normal?

I cleared /cache and dalvik cache - that didn't help

Answer 1

I had a similar problem before. In my case, the culprit was one or more background services. Deleting Google Goggles solved it for a while, then it came back.

This time, I removed Trust Go. So far, so good.

Whether or not you have those specific apps, I'd say there's a fair possibility that one of them is the problem.

I tracked it down by going to Settings > Developer Options and checking the box to overlay the processes on the screen. This is important because the act of using another app to check on what's happening can itself change things. I saw that even though a system process was eating all the CPU, Trust Go was frequently in the top five. Removing it seemed to cure it for me

Answer 2

Running Flappy Bird with no network results in heaps of these app_process instances running. Each uses about 7Mb of RAM and they don't go away. Using "OS Monitor" I have never seen app_process instances except for this.

However, killall app_process rebooted the phone so clearly there are other instances running, probably with changed identities. OS Monitor sees these, as does ps on my phone so for me, seeing app_process is never good.

I'd guess something has failed to start or failed to cleanup when exiting.