bus limits

[David Zeuthen]

Hi,

So, I've recently ran into the limits of the system message bus when
stress testing hal - (basically unplugging 10 USB devices at once,
leading to 50+ message calls at nearly the same time). The way I
discovered this was that some of the method calls to the service was
rejected by the bus with the message 'The maximum number of pending
replies per connection has been reached'. This limit, though
configurable from the system.conf file, defaults to 32. 

I do realize that the bus should be resistant to denial of service
attacks, but wouldn't it be better to just slow down traffic instead of
rejecting messages? Or at least make the limits per <policy> item in the
configuration file so e.g. messages from trusted sources, say hotplug
helpers, always get through. Because otherwise application programmers
will have to assume that every message can get lost and this leads to
more complicated code and thus more errors.

Cheers,
David