When a Docker image has been updated, will restarting the running container via docker restart pick up the change? Educated guess will be no, because like restarting a process, the memory is still retained. The best way to find out is to give a try.
A single Upstart job can have multiple instances running:
$ sudo start my-job port=4000
$ sudo start my-job port=4001
$ sudo start my-job port=4002
However, when the operating system reboots, the job with multiple instances will fail to start, due to instance information is not provided to the job. We can fix this problem by adding a for loop in the script section:
start on (local-filesystems and net-device-up IFACE!=lo)
stop on shutdown
for i in `seq 40004002`
With this Upstart job, we do not need to provide instance information:
$ sudo start my-job
Therefore, during system restart, the job will initiate automatically.