While playing with custom background workers, I noticed that postmaster does not notify its registered bgworkers if it receives SIGHUP, so you have to send a SIGHUP directly to the bgworker process to notify it. Signal handling is correctly done for SIGQUIT and SIGTERM for shutdown only. Attached is a patch fixing that, I simply added a call to SignalUnconnectedWorkers in SIGHUP_handler:postmaster.c.