How many socket connections possible?

linux sockets tcp max server-hardware
TheHippo picture TheHippo · Mar 16, 2009 · Viewed 192k times · Source

Has anyone an idea how many tcp-socket connections are possible on a modern standard root server? (There is in general less traffic on each connection, but all the connections have to be up all the time.)

EDIT: We will use a Linux Server.

Answer

shenedu picture shenedu · Mar 13, 2012

I achieved 1600k concurrent idle socket connections, and at the same time 57k req/s on a Linux desktop (16G RAM, I7 2600 CPU). It's a single thread http server written in C with epoll. Source code is on github, a blog here.

Edit:

I did 600k concurrent HTTP connections (client & server) on both the same computer, with JAVA/Clojure . detail info post, HN discussion: http://news.ycombinator.com/item?id=5127251

The cost of a connection(with epoll):

  • application need some RAM per connection
  • TCP buffer 2 * 4k ~ 10k, or more
  • epoll need some memory for a file descriptor, from epoll(7)

Each registered file descriptor costs roughly 90 bytes on a 32-bit kernel, and roughly 160 bytes on a 64-bit kernel.

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