Are deferred functions called when calling log.Fatalln?

问题

db, err := sql.Open("postgres", "…")
if err != nil {
    log.Fatalln(err)
}
defer db.Close()

tpl, err := template.ParseGlob("")
if err != nil {
    log.Fatalln(err)
}

If template.ParseGlob("") returns an error, is db.Close() still being called?

回答1:

No, the deferred functions aren't run.

Here's the description of log.Fatal :

Fatal is equivalent to Print() followed by a call to os.Exit(1).

log.Fatal calls os.Exit, whose description is here :

Exit causes the current program to exit with the given status code. Conventionally, code zero indicates success, non-zero an error. The program terminates immediately; deferred functions are not run.

Demonstration

If you really need to properly close resources or do some tasks before the program finishes, then don't use log.Fatal.

来源：https://stackoverflow.com/questions/17888610/are-deferred-functions-called-when-calling-log-fatalln