If systemd restarts MaxScale when an abnormal exit is detected, it is
likely to happen again. This leads into a loop which causes multiple
maxscale processes on the same machine. One example of this behavior is
when systemd times MaxScale out when it is starting.
The maxscale service will be restarted only if the process is down because
a signal was caught or the process times out. If the process would be restarted
when it exits with a non-zero value, this would lead to infinite loops when
there is a configuration error.
The fact that the maxscale process exits only after all services have been
started means that systemd will kill the maxscale process if starting the
services takes too long. Since the user authentication data is loaded on
startup and can take up a long time, there needs to be a longer than
default timeout for systems that use systemd.
