After the application accept kill -9 kill -15, it will be closed. Actually, program can control the shutdown flow by intercepting the signal from os, then you could shut down application safely.
Refer Graceful Shutdown Example Code.
go-concurrency-patterns/other/01-graceful/main.go
Lines 40 to 41 in 54f045e
In the example, you could use newNormalContext. Then shutdown program (ctrl+c) while the console prints 0. The console doesn't show 1 because program is closed accidentally.
But when use newGracefulContext, the console will print 1. Because it intercepts the signal, then program can prepare to shutdown in advance to avoid being closed accidentally.