Re: [Discuss-gnuradio] Debugging in gnuradio

[frankist]

Hmm... Thanks a lot. I think the problem may be related to the
connects/disconnects. Even if I am always reconnecting blocks, some freezes
happen sometimes in the disconnect() commands.

Is the patch you are refering to the new gnu version 3.5.3?

Also, I would like to know if there is a better method than the "sleep"
commands I used for letting the circuit for a short period of time. I mean,
I used a head block to select just a few samples at the end of the circuit,
but if I don't use the time.sleep(), the python script won't wait until I
get the number of samples I need. So what I am asking is a type of semaphore
command that lets the python script know when the gnuradio graph has already
finished.


Tom Rondeau-2 wrote:
> 
> On Thu, Apr 5, 2012 at 5:11 AM, frankist <address@hidden>
> wrote:
>>
>> It seems I found the solution, in spite of not knowing the reason.
>>
>> I just have to re-assign a new block to each block variable every time I
>> re-connect them. It seems that connecting and disconnecting the same
>> blocks
>> several times was the cause for the segmentation fault.
> 
> You shouldn't have to do that. What version of GNU Radio are you
> using, and are you on a 32-bit platform? This might be related to a
> bug in the disconnect/reconnect calls that was patched recently.
> 
> You can use the following link as a guide to debugging segfaults when
> they occur:
> 
> http://gnuradio.org/redmine/projects/gnuradio/wiki/FAQ#How-do-I-debug-GNU-Radio-in-Python
> 
> Tom
> 
> 
>> frankist wrote:
>>>
>>> Hi,
>>>
>>> I am having a hard time with a "segmentation fault" error. I am no
>>> expert
>>> in python (I just started to use it last week) but I find it difficult
>>> to
>>> believe that a segmentation fault error would appear in python code.
>>> However, I am not using any block made by me.
>>>
>>> So this is the part of my code where there is an segmentation fault:
>>>
>>> def measure_callback(self,kv):
>>>               print "Measuring!!"
>>>               if self.state==SNR_MEASURE:
>>>                       print "Measuring SNR"
>>>                       self.lock()
>>>                       self.disconnect((self.gr_file_source_0, 0),
>>> (self.gr_throttle_0,0), self.fft_sink)
>>>                       self.connect((self.gr_file_source_0, 0),
>>> (self.gr_complex_to_mag_squared_0, 0), (self.gr_moving_average_ff_1, 0),
>>> (self.gr_multiply_const_ff_0, 0), self.pwr_measure)
>>>                       self.unlock()
>>>                       time.sleep(5)
>>>                       snr_val=10*math.log(self.pwr_measure.level())
>>>                       print "SNR measured = ", snr_val
>>>                       self.lock()
>>>                       self.disconnect((self.gr_file_source_0,
>>> 0),(self.gr_complex_to_mag_squared_0, 0), (self.gr_moving_average_ff_1,
>>> 0), (self.gr_multiply_const_ff_0, 0), self.pwr_measure)
>>>                       self.connect((self.gr_file_source_0, 0),
>>> self.gr_throttle_0,
>>> self.fft_sink)
>>>                       self.unlock()
>>>
>>> So basically I am reading a signal from a file_source and showing its
>>> FFT
>>> on a graphical interface. Then when there is a callback from a button I
>>> made, this measure_callback(self,kv) is called and I change my circuit
>>> to
>>> measure SNR.
>>>
>>> I used some prints and discovered that the "segmentation fault" happens
>>> at
>>> "time.sleep(5)". Lol. Furthermore, the error doesn't happen all the
>>> times
>>> I run this code.
>>>
>>> Unfortunately, I don't know any type of debugging programs for gnuradio
>>> (I
>>> don't know if there is one) but it would be very handy because with just
>>> a
>>> "Segmentation Fault" message with no traceback it is difficult to know
>>> what to do.
>>>
>>> So, any suggestion about what might be causing this problem?
>>>
>>> Francisco
>>>
>>
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>>
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