Re: [Discuss-gnuradio] make test failure at qa_constellation_receiver

[Tom Rondeau]

On Fri, Apr 13, 2012 at 11:41 AM, Ben Reynwar <address@hidden> wrote:
> 2012/4/12 Alick Zhao <address@hidden>:
>> Hi all,
>>
>> Recently I have upgraded my gnuradio build to v3.5.3 on several
>> computers, and I find that on two machines with Ubuntu 11.10, make test
>> will fail the test qa_constellation_receiver while on the other two with
>> Fedora 16 all tests are passed.
>>
>> To investigate the problem, I add one line in the file
>> `gr-digital/python/qa_constellation_receiver.py` which just print the
>> value of constellation, differential, and correct before the assert.
>> Then I run the script
>> `build/gr-digital/python/qa_constellation_receiver_test.sh`. The output
>> is recorded and attached below. Among them:
>>
>> * test.t41.log is from a Thinkpad T41 with Ubuntu 11.10 32bit installed,
>> * test.t60.log is from a Thinkpad T60 with Ubuntu 11.10 32bit installed,
>> * test.f16.log is from a HP 6531s with Fedora 16 x86_64 installed.
>>
>> Hope these logs are helpful to diagnose the problem.
>>
>> PS: As a side note, my debugging line's output appears later than the
>> result, which is not the case for screen output. I think this is
>> probably related to stdout buffering.
>>
>> PS2: I once changed the REQ_CORRECT to 0.7 on one Ubuntu machine,
>> and then made the test passed. I wonder if it is a valid fix.
>>
>> alick
>>
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>>
>
> Weird.  This test is probabilistic (not ideal really) but the chance
> of it failing due to chance should be very small.  If it's
> consistently failing on one machine but not another then there's
> something fishy going on, and lowering REQ_CORRECT, while making the
> test pass, wouldn't help finding what's causing the problem.
>
> First thing I'd do would be to repeat the test a bunch of times and
> confirm you're getting a consistently higher BER on one computer than
> another.  Then I'd do a complete uninstall and reinstall of gnuradio
> on a computer having the issue.  If the problem is still there then
> it's probably going to be an unpleasant bug to find.
>
> Has anybody else seen this?
>
> Cheers,
> Ben


Alick,

I had seen that before, but it was a virtual machine installation of
11.10, 32-bit. I pinged Ben about it, but he didn't see same results
with a native install of 32-bit 11.10. I couldn't track down where the
problem was occurring or why, so I chalked it up to a problem with the
VM system.

Again, is anyone else having an issue like this? It appears to be
something really sneaky since most of the qa_constellation tests pass
with exactly the same numbers and results as they are expected to but
1 or 2 strangely deviate.

Thanks,
Tom