I worked out a small code which initializes about 1,000,000 nodes with some
attributes, and saw the memory usage on my linux machine (using 'top'
command). Then just later I averaged out the memory usage per node. I know
this is not the most accurate way but just for estimated value.
The kind of Node class I am working on in my original code is like :
class Node:
def __init__(self, #attributes ):
self.coordinates = coordinates
self.index = index
self.sibNum = sibNum
self.branchNum - branchNum
#here 'coordinates' and 'index' are LISTS with length = "dimension", where
"dimension" is a user-input.
The most shocking part of it after the memory-analysis was that, the memory
usage was never dependent on the "dimension". Yeah it varied a bit, but
there wasnt any significant changes in the memory usage even when the
"dimension" was doubled
-- Any clues?
Thank you for all your suggestions till this point.
Regards.
On Tue, Jul 7, 2009 at 1:28 AM, Antoine Pitrou wrote:
> mayank gupta gmail.com> writes:
> >
> > After a little analysis, I found out that in general it uses about
> > 1.4 kb of memory for each node!!
>
> How did you measure memory use? Python objects are not very compact, but
> 1.4KB
> per object seems a bit too much (I would expect more about 150-200
> bytes/object
> in 32-bit mode, or 300-400 bytes/object in 64-bit mode).
>
> One of the solutions is to use __slots__ as already suggested. Another,
> which
> will have similar benefits, is to use a namedtuple. Both suppress the
> instance
> dictionnary (`instance`.__dict__), which is a major contributor to memory
> consumption. Illustration (64-bit mode, by the way):
>
> >>> import sys
> >>> from collections import namedtuple
>
> # First a normal class
> >>> class Node(object): pass
> ...
> >>> o = Node()
> >>> o.value = 1
> >>> o.children = ()
> >>>
> >>> sys.getsizeof(o)
> 64
> >>> sys.getsizeof(o.__dict__)
> 280
> # The object seems to take a mere 64 bytes, but the attribute dictionnary
> # adds a whoppy 280 bytes and bumps actual size to 344 bytes!
>
> # Now a namedtuple (a tuple subclass with property accessors for the
> various
> # tuple items)
> >>> Node = namedtuple("Node", "value children")
> >>>
> >>> o = Node(value=1, children=())
> >>> sys.getsizeof(o)
> 72
> >>> sys.getsizeof(o.__dict__)
> Traceback (most recent call last):
> File "", line 1, in
> AttributeError: 'Node' object has no attribute '__dict__'
>
> # The object doesn't have a __dict__, so 72 bytes is its real total size.
>
>
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