Bug#791766: /usr/lib/cups/backend-available/usb: USB backend eats 100% CPU
On Wed 08 Jul 2015 at 12:01:57 +0200, Fabian Greffrath wrote:
> Hi there,
Hi there, Fabian. Thank you for your report.
> sometimes it happens that I print a file to a USB-attached printer
> and instead of printing, the usb process eats up 100% cpu. Nothing
> else happens, apart from some GNOME window popping up and asking if my
> printer is actually connected. In fact, it is.
The word "sometimes" isn't one which brings joy to the heart when bug
hunting. :)
How ofter does this happen? Has it just appeared with cups 2.0.3?
> This is what strace says the offending process does all the time:
>
> ioctl(15, USBDEVFS_CLAIMINTERFACE, 0x7fffad353bfc) = -1 EBUSY (Device
> or resource busy)
>
> This repeasts endlessly.
>
> Please tell me how I can provide further information.
The section "Testing a Backend and a Printer" at
https://wiki.debian.org/Dissecting and Debugging the CUPS Printing System
gives a way of trying to determine whether or not the backend is a cause
of your problem. We'll be assuming the filtering system is working ok
but you might want to set up debug logging and examine the error_log for
any untoward signs with filtering or sending the job to the printer.
If files sent directly to printer always print without issue it would
point to cups as the source of the trouble. If it helps, there is a way
of setting up directly printing to the printer as part of everyday
printing. It might take some of the tedium out of testing.
Regards,
Brian.
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