Aarti's questions

Nginx worker_connections "sets the maximum number of simultaneous connections that can be opened by a worker process. This number includes all connections (e.g. connections with proxied servers, among others), not only connections with clients. Another consideration is that the actual number of simultaneous connections cannot exceed the current limit on the maximum number of open files". I have few queries around this:

1. What should be the optimal or recommended value for this?
2. What are the downsides of using a high number of worker connections?

As mentioned in http://nginx.org/en/docs/http/ngx_http_upstream_module.html#keepalive

It should be particularly noted that the keepalive directive does not limit the total number of connections to upstream servers that a Nginx worker process can open. The connections parameter should be set to a number small enough to let upstream servers process new incoming connections as well.

I want to understand if a new client comes, why can't they use existing keep-alive connections?

Does Nginx need to create a new connection with upstream everytime a new client comes?