[Geomoose-users] wms source slow when tiled

[Mark Volz]

James,

Both applications are requesting about the same number of tiles when I zoom in on the map.  There's got to be something else that I am overlooking...



Mark Volz, GISP
GIS Specialist

From: James Klassen [mailto:klassen.js at gmail.com]
Sent: Thursday, September 19, 2013 11:19 AM
To: Mark Volz
Subject: Re: [Geomoose-users] wms source slow when tiled

My guess is you are loading too many tiles at once.  I had this problem on a local GeoMoose install (for a portable device with the browser and Apache/MapCache and MapServer all on the same machine).

What I was running up against was the browser will only initiate a limited number of simultaneous (4-8) connections to any particular server.  If you are downloading a lot of tiles and anything takes awhile to download (can even be a different non-tiled layer) some of the tiles can end up in the request queue behind the slower request.  Setting the OpenLayers buffer parameter larger worsens this effect (because it downloads many more offscreen tiles).  The solution in my case was to set buffer=0, and make sure all layers came in quickly.  Another possible solution could be to give DNS alias names to your MapCache server (and then use the alias name in the mapbook) so the browser counts the connection to get the tiles in a separate pool from the other layers.

Alternatively, but less likely, you may be exceeding the max-simultaneous requests on your server.

On 2013/9/19 10:57 AM, Mark Volz wrote:

Hello,



I am using mapcache to serve air photos for a geomoose application.  When I am using tiled="false" the air photos are rather fast.  I thought I would try to speed things up by changing tiled to true -which is what I did for another application.  However on this application, half of the pictures show up really fast, however the other pictures are either slow or they time out.  I'm not sure why this is running slow.  If anyone notices something that I did wrong let me know:



*         Mapcache works relatively fast when I am requesting a single image.

*         Mapcache is fast when I am serving tiles to other applications.

*         Every layer is using a single projection, which is the same one that the wms server uses.

*         The max_extent and the initial_extent in both the mapbook, and compiled.js match the mapcache extent.

*         The scales in the mapbook, and compiled.js match the resolutions in mapcache.





Please let me know if I missed a step.



Thanks







Mark Volz, GISP

GIS Specialist








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