How to increase the limits of open files (sockets) for a go program?

Question

go

The following errors are thrown in the go log
2017/03/08 08:11:11 http: Accept error: accept tcp [::]:9001: accept4: too many open files; retrying in 5ms
2017/03/08 08:11:11 http: Accept error: accept tcp [::]:9001: accept4: too many open files; retrying in 10ms
Actually in limits.conf
* soft nproc 200000
* hard nproc 200000
* soft nofile 200000
* hard nofile 200000
ulimit -n
200000
in sysctl.conf
fs.file-max = 99999999
but when I look at the limits on the app itself for some reason there is 1024 soft and 4048 hard
cat /proc/26602/limits
Limit Soft Limit Hard Limit Units
Max open files 1024 4096 files
How to increase the application limit?

Answer 1

As a result, it turned out that this is a default restriction that is imposed by systemd
In the service startup script, you need to prescribe
LimitNOFILE=200000
LimitNPROC=200000

Answer 2

But this is a crutch solution. How much can limits be increased? Isn't it more correct to figure out why there are so many open descriptors at the same time?