Re: [Bluez-users] Major slowdown when service discovery+opening a service happens on two systems trying to talk to each other

[Marcel Holtmann <marcel@holtmann.org>]

Hi Marc-Andre,

> I'm working on an application where every Bluetooth device is trying to
> scan for every other one around, and check if it runs my custom service.
> At the same time, said service is running in another thread, waiting to be
> connected to.
> 
> I am using Rococo with Bluez. Kernel RH2.4.28, latest version of BlueZ.
> Belkin FT003 dongles.
> 
> When I have one computer having the service opened+performing the scan,
> while the other just performs the scan, things go fine. The scans are
> timely and I can send a message.
> 
> However, then I have both computers running the service+the service scan,
> things slow down to a crawl. Actually, it depends on its mood.
>  It can take a full minute to have a device scan and a service scan
> completing, or less than 20 seconds! Sometimes, computer a  will be able
> to detect computer b, while B still shows no sign of life.
> 
> On top of things, if I manage to get it to send a message to its peer, the
> peer will get an Exception :( I was able to fix this by preventing the
> application from doing a service scan at the moment it would send, but
> that didn't fix the weird behaviour on service discovery. This hackaround
> is not sturdy and I don't like it as a general thing.
> 
> Has such thing ever happened to any of you? What can I do to fix it?
> 
> It looks like Bluetooth won't let me open a connection while doing a
> service scan. Is there limitations on what can be running simultaneously?
> It looks like service scan + opening connections is no good. Should I
> know other ones like that?

please speak in terms of the Bluetooth specification. What are you
doing? Inquiry, page, service discovery or what?

Regards

Marcel




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