[OSM-talk] Mapnik Tilecache Memory Error (Myanmar Cyclone Relief)

[Frederik Ramm]

Hi,

> Um... no. At least not if it does the sensible thing and maps it
> for shared read.

I don't think it is even possible to mmap somthing for "private read". 
The boost lib only ever sets the SHARED flag when it wants write access:

     void* data = ::mmap( hint, pimpl_->size_,
            readonly ? PROT_READ : (PROT_READ |PROT_WRITE),
            readonly ? MAP_PRIVATE : MAP_SHARED,
            pimpl_->handle_, p.offset );

I guess that a "shared" mode is implicitly used by mmap if you specify 
read access only; anything else would not make sense (and would mean 
that the boost guys got it wrong, which is not impossible but rare).

Bye
Frederik