Diogo Gomes Blog

When considering a project involving a large number of source files, compilation time is always an issue.
DistCC is in these cases a very good solution.
From DistCC site:

distcc is a program to distribute builds of C, C++, Objective C or Objective C++ code across several machines on a network. distcc should always generate the same results as a local build, is simple to install and use, and is usually much faster than a local compile

My problem was how to keep the $DISTCC_HOSTS variable updated, since computers in my lab never seam to be left alone (after all… this is a lab ).

My idea was therefore to use AVAHI and to come up with a simple unix pipe that would feed the $DISTCC_DIR/hosts file.

Here is my hack:

1. created /etc/avahi/services/distcc.service:
   

   <?xml version="1.0" standalone='no'?><!--*-nxml-*-->
<!DOCTYPE service-group SYSTEM "avahi-service.dtd">
<service-group>
<name replace-wildcards="yes">Distcc on %h</name>
<service>
<type>_distcc._tcp</type>
</service>
</service-group>


2. Install distcc and avahi-utils
   

   apt-get install distcc avahi-utils

3. edit /etc/defaultdistcc accordingly
4. add the following command to crontab:

avahi-browse _distcc._tcp -t -r | grep address | egrep -v : | cut -d [ -f 2 | cut -d ] -f 1 | paste -s -d’ ‘ > ~/.distcc/hosts

That’s it!

There is also a patch available for distcc to integrate avahi functionality in a more robust manner (for instance by hack will cause problems when compiling during the update of the file), but I didn’t want to patch my Ubuntu distcc version. Best of all it is much easier to distribute the distcc.service file then a patched version of distcc ;).