Re: [Numpy-discussion] Re: Garbage collection fails after numarray exception

29 Feb 2004


      On Sun, 2004-02-29 at 04:28, Leo Breebaart wrote:
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Rob Hooft  writes:
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On Tue, 2004-02-10 at 15:09, Leo Breebaart wrote:
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> import numarray
> a = numarray.zeros(100000000)
> del a
> a = numarray.zeros(100000000)
> a + ''
  Traceback (most recent call last):
    File "<stdin>", line 1, in ?
    File "/usr/lib/python2.3/site-packages/numarray/numarraycore.py", line 664, in __add__
      return ufunc.add(self, operand)
    File "/usr/lib/python2.3/site-packages/numarray/ufunc.py", line 870, in _cache_miss2
      (in1, in2), insig, scalar = _inputcheck(n1, n2)
    File "/usr/lib/python2.3/site-packages/numarray/ufunc.py", line 391, in _inputcheck    raise TypeError(
  TypeError: UFunc arguments must be numarray, scalars or numeric sequences
> del a
>
If I execute these statements alongside 'top' or another
memory monitor, I of course see a big memory increase after
each call to 'zeros', as well as a big decrease after the
first 'del a' -- but no change whatsoever any more after the
second 'del a', not even if I explicitly call the garbage
collector via the gc module. [...]
Hmm.... Isn't this the standard python thing that it keeps the
context of the last exception somewhere for queries? Just
This is a good point, something I rediscovered for myself a couple weeks
ago:  since Python holds onto the context at the point of an exception, 
it will keep arrays alive in the exception context.
...
...
generate another exception and you should see that the memory
taken by a is liberated because the indirect reference from
sys.exc_traceback to a disappears.
Well, I've tried to test this, but even after multiple subsequent
exceptions the memory taken up by the numarrays is not freed, at
least not on my machine and with Python 2.3.3. Does it work for
you if you try running the above code and then generating an
exception?
But... I looked into this some more and found that there were errors in
the exception handling for ufuncs which resulted in leaked memory.

Regards,
Todd

-- 
Todd Miller