Editing Distcc (section)

==Design==

distcc is designed to speed up compilation by taking advantage of unused processing power on other computers. A machine with distcc installed can send code to be compiled across the network to a computer which has the distccd [[daemon (computer software)|daemon]] and a compatible compiler installed.<ref name=drdobbs>{{cite web|author=Daniel Robbins |url=http://drdobbs.com/184401764 |title=Distcc & Distributed Computing |publisher=Dr.Dobb's |date=2004-02-01 |access-date=2011-08-24}}</ref>

distcc works as an agent for the compiler. A distcc daemon has to run on each of the participating machines. The originating machine invokes a [[preprocessor]] to handle header files, preprocessing directives (such as <code lang="C">#ifdef</code>) and the source files and sends the [[Translation unit (programming)|preprocessed source]] to other machines over the network via [[Transmission Control Protocol|TCP]] either unencrypted or using [[Secure Shell|SSH]]. Remote machines compile those source files without any local dependencies (such as libraries, header files or macro definitions) to object files and send them back to the originator for further compilation.<ref name=linuxgazette>{{cite web|author=V. L. Simpson |url=http://linuxgazette.net/107/simpson.html |title=Speed Compiling with Distcc |publisher=linuxgazette.net |date=October 2004 |access-date=2011-08-25}}</ref>

distcc version 3 supports a mode (called ''pump mode'') in which included header files are sent to the remote machines,
so that preprocessing is also distributed.