I’ve been working with python for quite a bit of time and I’m confused regarding few issues in the areas of Garbage Collection, memory management as well as the real deal with the deletion of the variables and freeing memory.
>>> pop = range(1000)
>>> p = pop[100:700]
>>> del pop[:]
>>> pop
[]
>>> p
[100.. ,200.. 300...699]
In the above piece of code, this happens. But,
>>> pop = range(1000)
>>> k = pop
>>> del pop[:]
>>> pop
[]
>>> k
[]
Here in the 2nd case, it implies that the k is just pointing the list ‘pop’.
First Part of the question :
But, what’s happening in the 1st code block? Is the memory containing [100:700] elements not getting deleted or is it duplicated when list ‘p’ is created?
Second Part of the question :
Also, I’ve tried including gc.enable and gc.collect statements in between wherever possible but there’s no change in the memory utilization in both the codes. This is kind of puzzling. Isn’t this bad that python is not returning free memory back to OS? Correct me if I’m wrong in the little research I’ve did. Thanks in advance.
Slicing a sequence results in a new sequence, with a shallow copy of the appropriate elements.
Returning the memory to the OS might be bad, since the script may turn around and create new objects, at which point Python would have to request the memory from the OS again.