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

[Zac Spitzer]

I have played around with this using image magic to slice tiles
and it's a massive improvement. the difference rendering one big tile 1600px sq
for tile whole screen and a 300px tile is quite negligible

the analogy with windows copying is really good !



z


On Wed, Apr 22, 2009 at 12:17 PM, UV <uvwild at gmail.com> wrote:
> 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.
>> _______________________________________________
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>> mapguide-internals at lists.osgeo.org
>> http://lists.osgeo.org/mailman/listinfo/mapguide-internals
>>
>
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-- 
Zac Spitzer -
http://zacster.blogspot.com
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