Busy loop in backendRunLoop (usb backend process hogs cpu)

[michaelrsweet]

Version: 1.3.2
CUPS.org User: jdarmochwal

I am using a Canon Pixma iP4300 with a proprietary driver and Cups 1.3.2 on a Linux PC.
When I start a print Job, a "gs" process (started by the printer driver) and a "usb" process each use about 50% of the cpu. The "usb" process obviously is in a busy loop, since there is no data ready to be sent to the printer.

That busy loop is the for-loop in backendRunLoop (backend/runloop.c)
In my case print_bytes is 0, side_cb is true, use_bc is false. The select call returns immediately, because output is ready. But since no data is available the loop just goes round and round.
I guess doing a select call just on the input file descriptors before the current select call would help.

[michaelrsweet]

CUPS.org User: mike

Dupe of STR #2664, already fixed in CUPS 1.3.6...