Too many file open issue on Production

We are facing**too many file open issue**on Production.We are using mattermost 7+ version. Almost 400+ users login on daily bases for internal organisation communication purpose. We have gradually increase file limit for it and now it is 17K but it reaches in 2, 3 days and we have to restart server for it. We have also done debugging but did not find helpful for it. Can you identify the root cause and solution of it.
I will be thank for it

This is a duplicate of Too many file open issue