404 tiles showing up with broken image symbol

[dittaeva]

Recently tiles that haven't been generated because of lack of content are showing up with 404 icons on the route overlay:

It does not look like this when I first visit the site, but when I come back to it, and is possibly affected by some shortcut or something else I do with the browser. This has happened quite a number of times now (perhaps since OpenLayers 2.12?), but I do not know if it always is with Chrome.

Missing tile warning is also standard behaviour in JOSM, and empty tiles instead of no tiles could make things more beautiful, but from this pingdom analysis it also seems it would make it much slower since 404s are much faster than files of comparable size.

[lonvia]

The handling of non-existent tiles was changed in OpenLayers 2.12 was changed. The new implementation fails sometimes but as of now I could not produce a reproducible test case to be able to fix that.

Sending empty tiles is not a simple change for the server side. In any case, I was thinking about sending a redirect because that would hopefully mean that the browser needs to do less caching.

[dittaeva]

Playing with the opacity slider patch from Joachim I discovered that I could turn "on and off" the broken link image with different opacities. Especially visible with the hill shading layer here.

[dittaeva]

Has this been reported to OpenLayers? Could it be related to this issue? I suppose this is the commit with the new behaviour.

[lonvia]

The new DB-based tile server returns empty tiles instead of 404s. This should solve this issue.