GoogleCodeExporter
commented
8 years ago it will try download this tile over and over againOriginal comment by hanhe...@gmail.com on 21 Aug 2013 at 3:19
Open GoogleCodeExporter opened 8 years ago
GoogleCodeExporter
commented
8 years ago it will try download this tile over and over againOriginal comment by hanhe...@gmail.com on 21 Aug 2013 at 3:19
GoogleCodeExporter
commented
8 years ago This is a known issue. Many times tiles are not available for short periods of
time. For example if a tile server is under heavy load then it may temporarily
deny access to a tile, but then later allow access once the load has lightened.
So we don't want to completely stop requesting a tile if it doesn't load on the
first request.
Some things to try:
1. Why are you requesting a tile that doesn't exist? If you don't have imagery
for a particular zoom level then you should limit the maps so the user is not
allowed to go to that zoom level. If you have control over the tile server, one
solution would be to return "loading" tiles or "imagery not available" tiles
instead of a 404 error.
2. One solution is to create a custom modular tile provider that adds an
artificial delay at the end of the tile provider chain. So if all the regular
modular tile providers fail then the custom provider will sleep for a few
seconds and then fail. After that the tile will be re-requested. This doesn't
prevent re-requesting the tile but it adds a delay so that it isn't getting
hammered constantly.
I don't know if this is something we will fix. The delayed tile provider is an
okay idea, but I don't know if it that is something we want to add by default
because some users may not appreciate what could be perceived as a "drop in
performance".
Original comment by kurtzm...@gmail.com on 21 Aug 2013 at 9:55
GoogleCodeExporter
commented
8 years ago some tile is a white picture, so was not on the server.I cannot change the
server.
adds a delay is a idea, I can try it.
thank youOriginal comment by hanhe...@gmail.com on 22 Aug 2013 at 1:41
GoogleCodeExporter
commented
8 years ago I do have the same issue with OpenSeaMap.
If there is no seamak, which is in average more than 99% of the tiles the
OpenSeaMap server sends back a 404 error.
See the last comment from the openseamap deveolpper at the bottom of this
thread.
http://forum.openseamap.org/viewtopic.php?id=1815 :
"OpenSeaMap tiles are transparent overlays with the same tile addressing
scheme, but is stored as a sparse array - where there is no Seamark image there
is no tile, so remember to handle 404s as a feature, not a bug! Malcolm
Herring, OpenSeaMap developer"
Could we inernally create a transparent tile after a certain number of retries?Original comment by henri.la...@gmail.com on 12 Feb 2014 at 6:28
GoogleCodeExporter
commented
8 years ago See also issue 13Original comment by neilboyd on 14 Feb 2014 at 9:56
GoogleCodeExporter
commented
8 years ago The idea of keeping track of failed 404 downloads and preventing them from
retrying after a certain number of failures has been tossed around for a while
- but a 404 is pretty final and although I don't think we should cache a 404,
why don't we just return a "tile imagery missing" image to the tile cache in
these cases?
The tricky part is preventing the file cache from saving the "tile imagery
missing" tile to the cache. Maybe we add a "no cache" flag to the tile object.Original comment by kurtzm...@gmail.com on 14 Feb 2014 at 2:31
Original issue reported on code.google.com by
hanhe...@gmail.comon 21 Aug 2013 at 3:09