[Zope-dev] transience and gc.set_threshold(1)

[Michael Dunstan]

On 6/10/2004, at 4:06 AM, Tim Peters wrote:

> [Michael Dunstan]
>> I'm seeing test failures in transience when running the tests for
>> Zope-2_7-branch (python 2.3.3) with garbage collection threshold0 set
>> to 1.
>> <snip>
> Whenever I see a test module import fauxtime, I run screaming in
> terror.  This seems to be like running the multiprocess ZEO tests
> (from which I run screaming daily <wink>):  "depending on" a gazillion
> timing accidents you can't control, sometimes they just fail.
>
> I ran the tests above in a loop a few hundred times on my box just
> now, with no failures, Python 2.3.4 and command line:
>
> test.py -vvLd -g1 --dir lib/python/Products/Transience/tests . 
> testPathological
>
> There's a big difference between my runs and yours, though:  running
> the two tests took about 4.6 seconds on your box, but takes about 1.8
> seconds on mine.  Now, for example, if I add
>
>         oldtime.sleep(3)  # approximately 4.6 - 1.8, on the high side
>
> right before
>
>         map(self.t.__delitem__, r)
>
> in testPathologicalRightBranching, then testPathologicalRightBranching
> fails every time in a way similar to your reported failure -- and even
> without -g1 on the command line.
>
> If I change the sleep to 1.5, then (with -g1 again) sometimes it
> passes, sometimes not, depending on how busy the box is doing other
> stuff at the same time.
>
> So that's A Problem.  Any test that adds a bunch of stuff to a
> TransientObjectContainer and expects to *find* it all there later is
> implicitly assuming that the test runs fast enough so that containees
> don't vanish before their containedness is checked.  I suspect you're
> seeing problems with -g1 here just because -g1 grossly slows the
> tests.

Doh! For some reason I had written that explanation off before posting. 
The pattern of missing keys did not seem consistent enough at the time.

But, as you say, as soon as I comment out the use of faxtime and run 
those same two tests they both pass just fine.

thanks
michael