Bug#758626: cups-browsed: uses a lot of CPU on a busy network

[Till Kamppeter <till.kamppeter@gmail.com>]

I by myself have never tested cups-browsed with that many printers or
otherwise very noisy networks. It is also the first time that someone
reports that cups-browsed takes a lot of CPU.

cups-browsed is running an event loop and if an event (= broadcast
signal from local avahi-daemon or from remote CUPS server) happens, a
callback function to create, update, or remove a print queue is executed.

Important to know is also what kind of broadcasting the remote servers
are doing. Are they running newer CUPS versions and so using Bonjour for
broadcasting (cups-browsed is then triggered by the local avahi-daemon)
or are these older servers using CUPS broadcasting (cups-browsed uses
the legacy CUPS browsing facility then)?

Can you deactivate CUPS browsing via cups-browsed.conf? If some printers
go away on your local system then you indded have servers using the old
method. Does the system load caused by cups-browsed go down now? Perhaps
upgrading old servers to have all broadcasting being Bonjour could help.

Is there a lot of Bonjour broadcasting in your network, also from other
devices, like file servers or so? You can see this running the
"avahi-discover" command.

Is your local machine sharing CUPS printers? Did you turn on the legacy
CUPS broadcasting of your local cups-browsed to share to old clients?
Try to turn this off and in case of success, update the CUPS on these
clients.

   Till