[OpenLayers-Users] OpenLayers apparently dropping tile requests when zooming quickly (?)

[Michael Katz]

A bit more info on this. I tried using the Fiddler HTTP 
debugging proxy to get a better idea of whether/when messages were 
getting lost. I was not able to reproduce the problem while messages 
were going through Fiddler. I don't know if this is because it made the 
message processing less bursty, or what. When I turned Fiddler off I was able to reproduce the problem again.

I am using the latest version of OpenLayers, version 2.11.


________________________________
From: Michael Katz <michaeladamkatz at yahoo.com>
To: "openlayers-users at lists.osgeo.org" <openlayers-users at lists.osgeo.org>
Sent: Friday, October 21, 2011 5:05 PM
Subject: [OpenLayers-Users] OpenLayers apparently dropping tile requests when zooming quickly (?)


(Sorry, I seem to have mistakenly appended this question to another thread. Reposting hopefully as its own topic.)


I am serving 256x256-pixel tiles (OpenLayers.Layer.XYZ) from my own local web server, which are overlayed on top of a Google base map.

If I repeatedly double-click on the openlayers map to zoom repeatedly, it fires off a rapid stream of tile requests to the local web server. However, I find that if often fails 
to fire the complete set of necessary requests for the final zoom level. For instance, suppose I zoom quickly from level 3 to level 8 by double-clicking on the center of the map five time. When I get to level 8, it might fill in only three of 
the nine visible overlay tiles in the view. As far as I can tell, the other six XYZ tile requests never were made by openlayers to the local web server. Is this expected behavior? For instance, is there some point at which 
openlayers stops issuing tile requests if there are too many requests outstanding?

(In my case it may take a few seconds to generate each tile, so there is indeed a backlog of tile requests for those zoom levels I quickly passed through. The Google basemap tiles, on the other hand, never seem to get lost, but I don't know if this is because they are served more quickly than my tiles, or what.)

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