[mapserver-users] static versus shared obj memory use

[Richard Greenwood]

Got it! Thanks for that explanation, it makes much more sense to me now.

Rich

On Fri, May 15, 2015 at 3:39 PM, Andy Colson <andy at squeakycode.net> wrote:

> "how many processes" is not very descriptive.  How many mapserve's vs how
> many different execuable.  Many mapserv's will share, but they wont share
> with any other executables.
>
> ogr/gdal might be a good example.  You have ogr compiled into mapserv.
> Running many mapserv's will all share the same code page in ram. However
> ogrinfo, ogr2ogr, etc wont be able to share with mapserv.
>
> -Andy
>
>
> On 5/15/2015 4:34 PM, Richard Greenwood wrote:
>
>> Thanks for the reply Andy. I had Googled a bit and found this
>> stackoverflow
>> <
>> http://stackoverflow.com/questions/2649334/difference-between-static-and-shared-libraries
>> >
>> discussion in which the answer at the bottom said:
>>
>>     "The most significant advantage of shared libraries is that there is
>>     only one copy of code loaded in memory, no matter how many processes
>>     are using the library. For static libraries each process gets its
>>     own copy of the code. This can lead to significant memory wastage."
>>
>> But I'm not sure if that's applicable with a web/fcgi application.
>>
>> rich
>>
>> On Fri, May 15, 2015 at 3:04 PM, Andy Colson <andy at squeakycode.net
>> <mailto:andy at squeakycode.net>> wrote:
>>
>>     On 5/15/2015 3:59 PM, Richard Greenwood wrote:
>>
>>         I'm working on Linux and have statically linked mapserv for
>>         convenience
>>         but now I'm wondering if it is adversely affecting memory use. For
>>         example, if I have five fcgi mapserv instance like:
>>             mapserv.fcgi?map=mapfile1.map
>>             mapserv.fcgi?map=mapfile2.map
>>             mapserv.fcgi?map=mapfile3.map
>>             mapserv.fcgi?map=mapfile4.map
>>             mapserv.fcgi?map=mapfile5.map
>>         Am I using more memory with my static build than if they all
>>         referencing
>>         the shared libmapserver.so?
>>
>>         Thanks,
>>         rich
>>
>>
>>     I believe you will pay for the cost of one executable, the others
>>     will share the code pages, but get their own data pages.
>>
>>     So no, you probably are not using more memory using static build.
>>
>>     -Andy
>>
>>
>>
>>
>> --
>> Richard W. Greenwood, PLS
>> www.greenwoodmap.com <http://www.greenwoodmap.com>
>>
>
>


-- 
Richard W. Greenwood, PLS
www.greenwoodmap.com
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