Editing IRCd (section)

=== Connections ===
Running a large IRC server, one that has more than a few thousand simultaneous users, requires keeping a very large number of [[Transmission Control Protocol|TCP connections]] open for long periods. Very few ircds are [[Thread (computer science)|multithreaded]] as nearly every action needs to access (at least read and possibly modify) the global state.

The result is that the best platforms for ircds are those that offer efficient mechanisms for handling huge numbers of connections in a single thread. [[Linux kernel|Linux]] offers this ability in the form of [[epoll]], in kernel series newer than 2.4.x. [[FreeBSD]] (since 4.1) and OpenBSD (since 2.9) offers [[kqueue]]. [[Solaris (operating system)|Solaris]] has had [https://web.archive.org/web/20070202231908/http://access1.sun.com/techarticles/devpoll.html /dev/poll] since version 7, and from version 10 onwards has [[IOCP]] (I/O Completion Ports). [[Windows]] has supported [[IOCP]] since Windows NT 3.5. The difference made by these new interfaces can be dramatic. IRCU developers have mentioned increases in the practical capacity per server from 10,000 users to 20,000 users.{{Citation needed|reason=Which developers? and When? |date=July 2022}}