Go 1.19 uses it during startup.
From the Go changelog:
> On Unix operating systems, Go programs that import package os now
> automatically increase the open file limit (RLIMIT_NOFILE) to the
> maximum allowed value; that is, they change the soft limit to match the
> hard limit. This corrects artificially low limits set on some systems
> for compatibility with very old C programs using the select system call.
> Go programs are not helped by that limit, and instead even simple
> programs like gofmt often ran out of file descriptors on such systems
> when processing many files in parallel. One impact of this change is
> that Go programs that in turn execute very old C programs in child
> processes may run those programs with too high a limit. This can be
> corrected by setting the hard limit before invoking the Go program.