hard memory limits

[Maurice LING]

John Machin wrote:
> On Sat, 07 May 2005 02:29:48 GMT, bokr at oz.net (Bengt Richter) wrote:
> 
> 
>>On Sat, 07 May 2005 11:08:31 +1000, Maurice LING <mauriceling at acm.org> wrote:
>>
>>>It doesn't seems to help. I'm thinking that it might be a SOAPpy 
>>>problem. The allocation fails when I grab a list of more than 150k 
>>>elements through SOAP but allocating a 1 million element list is fine in 
>>>python.
>>>
>>>Now I have a performance problem...
>>>
>>>Say I have 3 lists (20K elements, 1G elements, and 0 elements), call 
>>>them 'a', 'b', and 'c'. I want to filter all that is in 'b' but not in 
>>>'a' into 'c'...
>>>
>>>
>>>>>>a = range(1, 100000, 5)
>>>>>>b = range(0, 1000000)
>>>>>>c = []
>>>>>>for i in b:
>>>
>>>...     if i not in a: c.append(i)
>>>...
>>>
>>>This takes forever to complete. Is there anyway to optimize this?
>>>
>>
>>Checking whether something is in a list may average checking equality with
>>each element in half the list. Checking for membership in a set should
>>be much faster for any significant size set/list. I.e., just changing to
>>
>>     a = set(range(1, 100000, 5))
>>
>>should help. I assume those aren't examples of your real data ;-)
>>You must have a lot of memory if you are keeping 1G elements there and
>>copying a significant portion of them. Do you need to do this file-to-file,
>>keeping a in memory? Perhaps page-file thrashing is part of the time problem?
> 
> 
> Since when was 1000000 == 1G??
> 
> Maurice, is this mucking about with 1M or 1G lists in the same
> exercise as the "vm_malloc fails when allocating a 20K-element list"
> problem? Again, it might be a good idea if you gave us a little bit
> more detail. You haven't even posted the actual *PYTHON* error message
> and stack trace that you got from the original problem. In fact,
> there's a possible interpretation that the (system?) malloc merely
> prints the vm_malloc message and staggers on somehow ...
> 
> Regards,
> John

This is the exact error message:

*** malloc: vm_allocate(size=9203712) failed (error code=3)
*** malloc[489]: error: Can't allocate region

Nothing else. No stack trace, NOTHING.

maurice