[mapguide-internals] Release Build not working???? Debug build is fine!!! Architectural Solution: RFC 63

[UV]

I finally came to the conclusion that this has been caused by resource 
limits. (the  infamous Out Of Memory exception)
 
A memory limitation causes the mapping / rendering service to abort 
rendering the tile before all features are determined.
Its very interesting that the serialization enforced by STDOUT of the 
debug build solves this problem already!

Firstly this is a bug because the faulty Tile gets returned without an 
error message. (like #462)

However, this gives us as reason to suggest a redesign of the Tiling 
service.
Basically, the server does not do anything efficient if we start to 
request mutliple tiles of the same map and scale at the same time.
This is like windows copying. If you start n parallel copy streams 
between the same disks you end up thrashing your disk.

In our mapguide case this means that the server should maintain a 
request queue and serialize request to the same map and scale
and maybe even compute 4 - 16 tiles at once and slice them up on the 
bitmap level.
This does not seem very hard to do and will improve performance and 
stability of the mapguide server dramatically.

See also RFC 63

UV wrote:
> Hi,
>
> now for the second time I tried to run my 8GB map sample in a release 
> build.
> In the debug build the server renders all tiles just fine.
>
> When I did the same test with the release build the server created 
> only tiles in a single color - no more features....
> (the sea is blue.... the desert is beige) the good news is that its 
> deterministic..... the same wrong tiles each time.
>
> I ran the test suite.... OK 430 tests
> The server INFO Trace.log does not show anything special.
>
> The server is executed from the exact same location in the default 
> installation directory.... I verified the DLL versions....
> No error messages... the access.log shows the error free access to the 
> tiles..... but the computed tiles are crap.
>
> Anyone seen this before?
> Any idea what to look for? As its a release build and the debug 
> version is working sorting this out is a challenging task.
> If there were any error messages this would be useful but there aint any.
>
> PS:
> The server repeatedly creates an additional directory in the tilecache 
> called C-0 (as opposed to C0)
> containing also very boring featureless tiles  named 0_-1.png to 
> 9_-1.png. This looks like a bug.
> _______________________________________________
> mapguide-internals mailing list
> mapguide-internals at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/mapguide-internals
>