Re: [mapserver-users] Mapcache - best way to find broken or white tiles in a service?

[Mark Volz]

Travis,

Thank you for your ideas.  The tiles themselves existed in Mapcache as white 
images so Mapcache returned a “valid” image instead of a 404.  I was able to 
find the white tiles by just deleting all the <1K files in the area.  However, 
if I ever notice the issue again I will definitely consider using the 
mapcache_seed command line with a shapefile to force the tiles to rebuild...  
That would have been quicker than searching for small files!

Thank You!

Sincerely,
Mark Volz, GISP
Lyon County GIS Coordinator

From: Travis Kirstine 
Sent: Wednesday, February 20, 2019 12:45 PM
To: Mark Volz 
Cc: mapserver-users@lists.osgeo.org
Subject: Re: [mapserver-users] Mapcache - best way to find broken or white 
tiles in a service?

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You shouldn't have any cached "broken" tiles unless your source WMS is 
generating the white images (metatiles).  I believe MapCache will generate a 
404 and return a empty tile if configured.  This may be the white tiles you are 
seeing.

   
   report

It can be very difficult to locate and clean up tiles from a cache, the easiest 
method and in some cases the fastest is simply to create a new cache and delete 
the old one.  One alternative is to use the mapcache_seed command line tool to 
either -f force the creation of new tiles or use the -mode delete option to 
delete the tiles from the cache.  BTW you can use a polygon (shapefile) with 
mapcache_seed to only update / delete the desired area using the -d flag.

Also if you are using a disk cache you might be using symlinks which will allow 
mapcache to "reuse" blank tiles.  If this is the case you might need to find / 
delete the symlinks rather than a "file"


   
   /tmp
   
   




On Tue, 19 Feb 2019 at 16:47, Mark Volz 
mailto:markv...@co.lyon.mn.us>> wrote:
Hello,

On my webmap I noticed a few broken (white) tiles in a single area from my 
mapcache server.  I would like to know the best way to find broken tiles in my 
mapcache service.

• Initially I was concerned that I would need to the tile number and 
folder location by using the BBOX, WIDTH, and TILE RESOLUTION from the request. 
 However, I figured out using the mapcache demo is easier to work with 
/mapcache/demo/

• Would it be better just to delete any tile that is 1K or smaller?  
These problibly are tiles that are broken, or intended to be blank in the first 
place.

• What do others do to validate that the mapcache tiles have been built 
appropriately?
Thanks!

Sincerely,
Mark Volz, GISP
Lyon County GIS Coordinator

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Re: [mapserver-users] Mapcache - best way to find broken or white tiles in a service?

[Travis Kirstine]

You shouldn't have any cached "broken" tiles unless your source WMS is
generating the white images (metatiles).  I believe MapCache will generate
a 404 and return a empty tile if configured.  This may be the white tiles
you are seeing.

   
   report

It can be very difficult to locate and clean up tiles from a cache, the
easiest method and in some cases the fastest is simply to create a new
cache and delete the old one.  One alternative is to use the mapcache_seed
command line tool to either -f force the creation of new tiles or use the
-mode delete option to delete the tiles from the cache.  BTW you can use a
polygon (shapefile) with mapcache_seed to only update / delete the desired
area using the -d flag.

Also if you are using a disk cache you might be using symlinks which will
allow mapcache to "reuse" blank tiles.  If this is the case you might need
to find / delete the symlinks rather than a "file"


   
   /tmp
   
   




On Tue, 19 Feb 2019 at 16:47, Mark Volz  wrote:

> Hello,
>
>
>
> On my webmap I noticed a few broken (white) tiles in a single area from my
> mapcache server.  I would like to know the best way to find broken tiles in
> my mapcache service.
>
> · Initially I was concerned that I would need to the tile number
> and folder location by using the BBOX, WIDTH, and TILE RESOLUTION from the
> request.  However, I figured out using the mapcache demo is easier to work
> with /mapcache/demo/
>
> · Would it be better just to delete any tile that is 1K or
> smaller?  These problibly are tiles that are broken, or intended to be
> blank in the first place.
>
> · What do others do to validate that the mapcache tiles have been
> built appropriately?
>
> Thanks!
>
>
>
> Sincerely,
>
> *Mark Volz, GISP*
>
> *Lyon County GIS Coordinator*
>
>
> ___
> mapserver-users mailing list
> mapserver-users@lists.osgeo.org
> https://lists.osgeo.org/mailman/listinfo/mapserver-users
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[mapserver-users] Mapcache - best way to find broken or white tiles in a service?

[Mark Volz]

Hello,

On my webmap I noticed a few broken (white) tiles in a single area from my 
mapcache server.  I would like to know the best way to find broken tiles in my 
mapcache service.

* Initially I was concerned that I would need to the tile number and 
folder location by using the BBOX, WIDTH, and TILE RESOLUTION from the request. 
 However, I figured out using the mapcache demo is easier to work with 
/mapcache/demo/

* Would it be better just to delete any tile that is 1K or smaller?  
These problibly are tiles that are broken, or intended to be blank in the first 
place.

* What do others do to validate that the mapcache tiles have been built 
appropriately?
Thanks!

Sincerely,
Mark Volz, GISP
Lyon County GIS Coordinator

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