Re: [Discuss-gnuradio] Debugging in gnuradio

[Tom Rondeau]

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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