mmap caching

[George Sakkis]

Dennis Lee Bieber wrote:

> On 21 Jan 2007 13:32:19 -0800, "George Sakkis" <george.sakkis at gmail.com>
> declaimed the following in comp.lang.python:
>
> >
> > The file is written once and then opened as read-only, there's no
> > flushing. So if caching is completely up to the OS, I take it that my
>
> 	How large is said file? While the OS should handle swapping pages as
> needed, you do have to recall that those pages are /mapped/ into the
> process virtual address space. Trying to mmap a 2GB file into a process
> that is already using 1GB of memory may not work (what is the default
> Windows split? 2GB process and 2GB shared OS?)

It's around 400MB. As I said, I cannot reproduce the MemoryError
locally since I have 1GB physical space but IIRC the user who reported
it had less. Actually I am less concerned about whether a MemoryError
is raised or not in this case and more about the fact that even if
there's no exception, the program may suffer from severe thrashing due
to constant swapping. That's an issue with the specific
program/algorithm rather with Python or the OS.

George