* Jeremy:
I have been using Python for several years now and have never run into
memory errors…
until now.
My Python program now consumes over 2 GB of memory and then I get a
MemoryError. I know I am reading lots of files into memory, but not
2GB worth. I thought I didn't have to worry about memory allocation
in Python because of the garbage collector. On this note I have a few
questions. FYI I am using Python 2.6.4 on my Mac.
1. When I pass a variable to the constructor of a class does it
copy that variable or is it just a reference/pointer? I was under the
impression that it was just a pointer to the data.
Uhm, I discovered that "pointer" is apparently a Loaded Word in the Python
community. At least in some sub-community, so, best avoided. But essentially
you're just passing a reference to an object. The object is not copied.
2. When do I need to manually allocate/deallocate memory and when
can I trust Python to take care of it?
Python takes care of deallocation of objects that are /no longer referenced/.
3. Any good practice suggestions?
You need to get rid of references to objects before Python will garbage collect
them.
Typically, in a language like Python (or Java, C#...) memory leaks are caused by
keeping object references in singletons or globals, e.g. for purposes of event
notifications. For example, you may have some dictionary somewhere.
Such references from singletons/globals need to be removed.
You do not, however, need to be concerned about circular references, at least
unless you need some immediate deallocation.
For although circular references will prevent the objects involved from being
immediately deallocated, the general garbage collector will take care of them later.
Cheers & hth.,
- Alf
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