mmap and shared memory

Nikita the Spider NikitaTheSpider at gmail.com
Thu Feb 14 21:53:49 CET 2008


In article <C5ydnQgAo_Q8Ii7anZ2dnUVZ_uCinZ2d at comcast.com>,
 Jeff Schwab <jeff at schwabcenter.com> wrote:

> Nikita the Spider wrote:
> > In article <Ko2dncp9M48X4S_anZ2dnUVZ_ryqnZ2d at comcast.com>,
> >  Jeff Schwab <jeff at schwabcenter.com> wrote:
> > 
> >> greg wrote:
> >>> Carl Banks wrote:
> >>>> In C you can use the mmap call to request a specific physical location
> >>>> in memory (whence I presume two different processes can mmap anonymous
> >>>> memory block in the same location)
> >>> Um, no, it lets you specify the *virtual* address in the process's
> >>> address space at which the object you specify is to be mapped.
> >>>
> >>> As far as I know, the only way two unrelated processes can share
> >>> memory via mmap is by mapping a file. An anonymous block is known
> >>> only to the process that creates it -- being anonymous, there's
> >>> no way for another process to refer to it.
> >> On POSIX systems, you can create a shared memory object without a file 
> >> using shm_open.  The function returns a file descriptor.
> > 
> > Sorry I missed the OP, but you might be interested in this shared memory 
> > module for Python:
> > http://NikitaTheSpider.com/python/shm/
> 
> 
> Thanks; I just downloaded it.  It seems to be missing the INSTALL file; 
> any idea where I could find that, or should I write to the author?

The main author has been AWOL for some years now. I'm the current 
maintainer. Sorry about the missing INSTALL file. Looks like I made 
reference to it in the README but never created it. It installs with the 
normal setup.py:

sudo python setup.py

I'll put out an updated package with an INSTALL file one of these days. 
Thanks for pointing that out.

Cheers

-- 
Philip
http://NikitaTheSpider.com/
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