libev

libev: "A full-featured and high-performance (see benchmark) event loop that is loosely modelled after libevent, but without its limitations and bugs. It is used, among others, in the GNU Virtual Private Ethernet and rxvt-unicode packages. Features include child/pid watchers and periodic timers based on wallclock (absolute) time (in addition to timers using relative timeouts), as well as epoll/kqueue/ports support, fast timer management, time jump detection and correction, and ease-of-use. It can be used as a libevent replacement using its emulation API or directly embedded into your programs without the need for complex configuration support. A full-featured and well-documented perl interface is also available."