Because it is possible to run multiple sett instances at the same time, we should make PID part of log output as well

It is possible to run multiple sett instances (via terminal, CLI or GUI). And all these instances could run different processes at the same time. However, they all output to the same log.

Either add PID (or anything uniquely identifying the sett instance in such cases) to log output. Or each instance should produce its own log. Or ....