[MapProxy] fast 0 byte responses in stead of tiles

[Steven Ottens]

Thanks, will try that.

But the problem is not that certain requests fail, but that after a 
certain point all requests fail; the ones that I'm a 100% sure are valid 
and cached in the sqlite, also all the layers fail at that point.

So something trigger Mapproxy to deliver empty tiles to all the 
requests, but since I don't know what causes the failure it is also hard 
to trigger it.


On 23-10-19 22:06, Travis Kirstine wrote:
> Hard to say what the issue is,  I would test the service using the 
> mapproxy-util serve-develop tool in debug mode and watch for errors.
>
> mapproxy-util serve-develop -b myserver.com:8585 
> <http://myserver.com:8585> mapproxy.yaml --debug
>
> Go to the demo site myserver.com:8585 <http://myserver.com:8585> and 
> turn on the browsers developer tools and try to generate errors
>
> My guess is either it failed to get the image from the WMS or failed 
> to write it to the mbtiles cache due to sqllite table locking.
>
> https://mapproxy.org/docs/nightly/configuration.html see bulk_meta_tiles
>
>
> On Wed, 23 Oct 2019 at 06:01, Steven Ottens <steven at minst.net 
> <mailto:steven at minst.net>> wrote:
>
>     Hi,
>
>     I've been asked to investigate why a MapProxy setup sometimes
>     fails to
>     deliver tiles. It is mapproxy 1.9 on a VMware server with windows
>     server
>     2012 and network attached storage. It is (obviously) not my setup,
>     nor
>     well documented :( but what I can see it is running as a windows
>     service
>     using cherrypy and python2.7
>
>     All the layers are mbtile-caches looking at Geoserver WMS (which runs
>     fine) and they are usually fast and I don't see any heavy server
>     load,
>     nor is it running out of memory.
>
>     However every now and then mapproxy stops delivering the actual
>     tiles,
>     but instead delivers within ~20ms an empty tile of 0 bytes. The logs
>     seem to be fine, but I'm not entirely sure where I should be looking.
>     Once I restart mapproxy all is fine again.
>
>     So the question is what might cause mapproxy to deliver empty
>     tiles for
>     valid requests, in stead of error messages/log messages?
>
>     Cheers,
>
>     Steven
>
>     BTW. I understand upgrading to a newer version should be a first
>     step,
>     but apart from the fact that I don't know (yet) how to upgrade a
>     windows
>     service, I don't like to blindly upgrade the software without
>     understanding the root cause of the problem
>
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