[ros-users] Wifi communication getting slow

[Josh Faust]

0 means an infinite queue.
On Jan 6, 2011 8:37 AM, "Cedric Pradalier" <cedric.pradalier at gmail.com>
wrote:
> Hello Josh,
>
> While trying to reproduce the delay build-up, I checked that the
> behaviour you described is the one I observe, as long as my message
> queue is positive.
>
> However, I could reproduce the behaviour when the message queue is zero:
> ros::Subscriber sub = n.subscribe("chatter", 0, chatterCallback);
>
> What is the intended behaviour in this case? I might have thought that
> zero would disable the queue when I wrote the code earlier...
> I guess the subscribe functions should document the semantic or flag
> an error if the value is invalid.
>
> Find my test programs attached. I'm postponing filing a ticket until I
> understand if there is a mistake somewhere else than in my code :)
>
> Best.
>
> On Wed, Jan 5, 2011 at 7:38 PM, Josh Faust <jfaust at willowgarage.com>
wrote:
>>> In this case, I was getting message build-up even with when the
>>> subscriber used a queue size of one. It seems that the teleop message
>>> where small enough to accumulate in the TCP kernel or HW buffer and
>>> not being discarded while the callback was running. This can be easily
>>> identified by looking at the message timestamp. In our case, the
>>> message age was increasing (obviously, you can only evaluate that on
>>> machines with synchronised clocks).
>>
>> If you have a way to reproduce this, please file a ticket -- roscpp
should
>> be draining the sockets as quickly as possible whether or not your
callbacks
>> take a long time.  They should be totally decoupled.
>> Josh
>>
>> _______________________________________________
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>> ros-users at code.ros.org
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>>
>>
>
>
>
> --
> Cedric Pradalier
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