Amit Dev wrote:
I'm observing a strange memory usage pattern with python strings on
Freebsd. Consider
the following session. Idea is to create a list which holds some
strings so that cumulative characters in the list is 100MB.
l = []
for i in xrange(100000):
... l.append(str(i) * (1000/len(str(i))))
This uses around 100MB of memory as expected and 'del l' will clear that.
for i in xrange(20000):
... l.append(str(i) * (5000/len(str(i))))
This is using 165MB of memory. I really don't understand where the
additional memory usage is coming from. [Size of both lists are same]
Python 2.6.4 on FreeBSD 7.2. On Linux and windows both uses around
100mb memory only.
A lot depends on the behavior of the system malloc(), and also the
reporting tools.
Python's internal allocator is only used for objects up to 256 bytes;
over that the request is passed to the platform malloc().
At a guess, a lot of your requests in the second case are over 4096
bytes (a single page of memory) and so the allocator is probably padding
the requests out to 2 pages, which is roughly in proportion with the
memory consumption you report.
jemalloc's behaviour can be tailored a bit - you might want to read the
man page.
--
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Andrew I MacIntyre "These thoughts are mine alone..."
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