[cups] Throttle misbehaving CUPS clients

[Michael Sweet]

Alex,

Please file a CUPS.org bug for this as well; I can't guarantee we'll come up with anything, but we can at least try it to see if it will help...

https://www.cups.org/str.php


On Aug 9, 2014, at 3:25 PM, Alex Korobkin <korobkin+cups at gmail.com> wrote:

> Hi Michael,
> 
> Yes, I did file a bug at https://bugzilla.gnome.org/show_bug.cgi?id=711446
> last year, but there hasn't been any action on it yet. Chrome team had
> received a similar bug report, didn't provide any updates.
> 
> If CUPS would wait a second or two (configurable parameter) before replying
> when it detects too frequent requests, then that would be enough to
> throttle bad clients. Even if they drop the connection and reopen it, it is
> not a big deal, they will get slowed down again. And naturally, this
> mechanism should be turned off by default for the majority of users,
> because this problem is likely to appear only in environments with large
> number of clients.
> 
> 
> 
> 2014-08-09 7:42 GMT-04:00 Michael Sweet <msweet at apple.com>:
> 
>> Alex,
>> 
>> Right now CUPS provides a MaxClientsPerHost directive that can limit the
>> number of simultaneous connections, but not a directive that limits the
>> rate of consecutive connections that are allowed.
>> 
>> I'm not sure how we would limit the latter, short of accepting he
>> connection and then not responding for some period of time which could
>> cause the client to timeout and try another connection.,,
>> 
>> Have you reported this bug to the gnome folks?
>> 
>> Sent from my iPad
>> 
>>> On Aug 9, 2014, at 1:55 AM, Alex Korobkin <korobkin+cups at gmail.com>
>> wrote:
>>> 
>>> Hi all,
>>> 
>>> I frequently encounter a situation where a printserver is experiencing
>> high
>>> load because of a misbehaving Linux client polling printers several times
>>> per second. I have no control over client machines, and the culprits are
>>> usually Gnome printing dialogs or Chrome.
>>> 
>>> It would be nice to have a mechanism in CUPS that would allow for
>>> throttling all requests from the same client a little bit: no more than
>> one
>>> request in 5 seconds, for example.
>>> 
>>> --
>>> -Alex
>>> _______________________________________________
>>> cups mailing list
>>> cups at cups.org
>>> https://www.cups.org/mailman/listinfo/cups
>> _______________________________________________
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>> 
> 
> 
> 
> -- 
> -Alex
> _______________________________________________
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> cups at cups.org
> https://www.cups.org/mailman/listinfo/cups

_________________________________________________________
Michael Sweet, Senior Printing System Engineer, PWG Chair