Re: Python memory usage

[petercable@gmail.com]

On Oct 21, 5:19 pm, Rolf Wester <rolf.wes...@il t.fraunhofer.de wrote:

Hi,
>
I have the problem that with long running Python scripts (many loops)
memory consumption increases until the script crashes. I used the
following small script to understand what might happen:
>

<snip>

AFAIK, python uses malloc behind the scenes to allocate memory. From
the malloc man page...

"The malloc() and free() functions provide a simple, general-purpose
memory allocation package. The malloc() function returns a pointer to
a block of at least size bytes suitably aligned for any use. If the
space assigned by malloc() is overrun, the results are undefined.

The argument to free() is a pointer to a block previously allocated by
malloc(), calloc(), or realloc(). After free() is executed, this space
is made available for further allocation by the application, though
not returned to the system. Memory is returned to the system only
upon termination of the application. If ptr is a null pointer, no
action occurs. If a random number is passed to free(), the results are
undefined."

HTH,

Pete

[David Cournapeau]

Re: Python memory usage

On Wed, Oct 29, 2008 at 6:56 PM, petercable@gmai l.com
<petercable@gma il.comwrote:

On Oct 21, 5:19 pm, Rolf Wester <rolf.wes...@il t.fraunhofer.de wrote:

>Hi,
>>
>I have the problem that with long running Python scripts (many loops)
>memory consumption increases until the script crashes. I used the
>following small script to understand what might happen:
>>

<snip>
>
AFAIK, python uses malloc behind the scenes to allocate memory. From
the malloc man page...
>
"The malloc() and free() functions provide a simple, general-purpose
memory allocation package. The malloc() function returns a pointer to
a block of at least size bytes suitably aligned for any use. If the
space assigned by malloc() is overrun, the results are undefined.
>
The argument to free() is a pointer to a block previously allocated by
malloc(), calloc(), or realloc(). After free() is executed, this space
is made available for further allocation by the application, though
not returned to the system. Memory is returned to the system only
upon termination of the application. If ptr is a null pointer, no
action occurs. If a random number is passed to free(), the results are
undefined."

Depending on your malloc implementation, that may not be true. IN
particular, with glibc, bit allocations are done with mmap, and those
areas are unmaped when free is called; any such area is immediatly
returned to the system

http://www.gnu.org/software/libtool/manual/libc/Malloc-Tunable-Parameters.html#Malloc-Tunable-Parameters

David