I have darkice that is transmitting a stream to an icecast server. Icecast is started by systemd. When the USB device is disconnected I see in the logs
Apr 09 12:24:32 scanner1 darkice: DarkIce: AlsaDspSource.cpp:265: No such device 
Which I would expect since the device was removed. When this happens icecast does not die but simply hangs. This is on a CentOS system. I ideally would like for darkice to die so that systemd could see that and then restart darkice.