Hi Thomas,

This sounds like an important core ROS ticket. Can you open a ticket
on the ROS wiki? Python 2.7 isn't officially supported as far as I can
tell, so I'm not sure how high a priority it will get. But this is
definitely one that should be tracked.

Thanks,
Blaise

On Mon, Jan 17, 2011 at 5:28 PM, Tomas Vanderka
<tomas_vanderka@tempest.sk> wrote:
> On 01/17/2011 08:36 PM, Blaise Gassend wrote:
>>>
>>> I somehow got dynparam get ... to work once, but i'm not sure what i
>>> did, next time i tried it, it got stuck as usual. I tried to run
>>> gdb/strace on it and it looks deadlocked waiting on semaphore. I also
>>> looked through logs and it seems dead just before subscribing to
>>> /dynamic_reconfigure_test_server/parameter_updates. Maybe python2.7 in
>>> fedora 14 has something to do with that? The client never gets
>>> subscribed>  never gets parameter_updates msg>  waits forever. Any
>>> suggestions how I can debug it further?
>>
>> Can you try with python 2.6?
>>
>> Do other python nodes work well?
>>
>> Have you inserted prints in the dynamic reconfigure client code to try
>> to figure out where it is getting stuck?
>
> My point is getting it working under fedora 14 so python-2.7 is a given.
>
> I was playing around a bit with simple python pub/sub examples and it looks
> like it is some kind of a race condition between multiple succeeding
> subscriptions under same nodehandle/prefix like /a/chatter1, /a/chatter2. It
> is not limited to dynamic_reconfigure.
>
> It happens with both cpp and python publishers but only with a python
> subscriber. c++ subscriber always works fine.
>
> I modified src/dynamic_reconfigure/client.py like this
>         self._updates_sub      =
> self._get_subscriber('parameter_updates',...
> +        rospy.sleep(1)
>         self._descriptions_sub =
> self._get_subscriber('parameter_descriptions',...
>
> and now it works.
>
> I tested it with talker/listener tutorials modified with attached patch, and
> it randomly works ok, only with one topic or not at all.
>
> v.
>
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