how to create multi connection from one machine to test my web server?

I wrote a web server and i want to check his performance when there are multi client request at same time.

This server hold GIS information about any connected client - so the server allocate a lot of memory for each connected client.

The client connected by using browser ( like chrome ). What i want is to run more then 10K client connection but i don't have more then 10K machine to run browser on each of them.

does there is some other way to do it? I must know when my server will be crash or slow down.