Is there a way to get the service alive?

[mperezfra]

When the phone goes to sleep or I change to other app for a while, Android kills the service. I get the following error

ActivityManager: Stopping service due to app idle u0a262 -1m55s386ms org.kivy.oscservice/.ServicePong

Is there a way to get the service alive in these situations?

[RobertFlatt]

@mperezfra
I changed the service to resume on app on_resume()
Because the stop() code does not work, I previously made these changes #9 (comment)

In on_resume(), I detect no response from the service, and restart it. Restart requires an elegant termination.

I expect there are issues that I have not considered, but this appears to work on Windows and Android.

Code fragments:

main .py:
server.bind(b'/alive', self.alive_response)

# ask if the service is alive
def ask_service_alive(self):
    self.im_alive = False
    self.client.send_message(b'/alive', [])
    # check for response after a short time
    Clock.schedule_once(self.check_alive,0.1)

# the response, which we may not get
def alive_response(self, message):
    self.im_alive = message.decode('utf8') == 'alive'

# check for no response
def check_alive(self, dt):
    if not self.im_alive:
        # lets hope whatever killed the service cleaned up afterwards
        self.start_service()

# a user might hope this would resume a service
def on_resume(self):
    if self.service:
        self.ask_service_alive(True)

service.py :

def alive():
    CLIENT.send_message(
        b'/alive',
        ['alive'.encode('utf8'), ],
    )

stopped = False

def stop(*_):
    global stopped
    stopped = True
    
if __name__ == '__main__':
    SERVER = OSCThreadServer()
    SERVER.listen('localhost', port=3000, default=True)
    SERVER.bind(b'/ping', ping)
    SERVER.bind(b'/stop', stop)
    SERVER.bind(b'/alive', alive)
    SERVER.getaddress()
    while True:
        sleep(1)
        if stopped:
            break
        send_date()
    SERVER.terminate_server()
    sleep(0.1)
    SERVER.close()

The choice to restart the service on_resume() is totally arbitrary. One could perhaps have two services restarting each other......

The unanswered question is what causes Android to stop the service? ( other than because it can)
These are not exactly helpful:
https://developer.android.com/guide/components/services#Basics
https://developer.android.com/reference/android/app/Service

More interesting how can one write a service that is unlikely to be stopped?
I have not seen an Android stop yet, but I'm restarting; and because of the way the demo is written I wouldn't.