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

[Ben Reynwar]

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