SIGTERM

Signal 15, and what kill sends when you name no signal: kill 1841 and kill -15 1841 are the same command. It is a request, not an execution. The program decides what happens next, and one written to handle it finishes the request in flight, writes its buffered bytes to disk, closes its database connection, removes its lock file, then exits. That takes real time: milliseconds for an HTTP request, sometimes a minute for a database. Counting to three and reaching for -9 interrupts exactly the work that was protecting your data. systemd's patience is written down: DefaultTimeoutStopUSec=1min 30s, ninety seconds before it escalates. And kill's silence only means the kernel accepted the signal, not that the process stopped; kill -0 1841 is how you check.