[mapserver-users] static versus shared obj memory use

[Andy Colson]

"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>