This port contains the userland implementation of Grand Central Dispatch
technology.

The central insight of GCD is shifting the responsibility for managing threads
and their execution from applications to the operating system. As a result,
programmers can write less code to deal with concurrent operations in their
applications, and the system can perform more efficiently on single-processor
machines, large multiprocessor servers, and everything in between. Without a
pervasive approach such as GCD, even the best-written application cannot
deliver the best possible performance, because it doesn'tt have full insight
into everything else happening in the system.

WWW: http://libdispatch.macosforge.org/