Mod_Tile handing off to renderd when tiles exist

Question

I have tiles rendered for zoom 0-13, and yet when I bring up the map with renderd running in debug mode I can see it making requests:

renderd[18553]: DEBUG: Got incoming connection, fd 8, number 1
renderd[18553]: DEBUG: Got incoming request with protocol version 2
renderd[18553]: DEBUG: Got command RenderLow fd(8) xml(tiles), z(8), x(47), y(100), mime(image/png), options()
renderd[18553]: DEBUG: START TILE tiles 8 40-47 96-103, age 5.93 days
renderd[18553]: Rendering projected coordinates 8 40 96 -> -13775786.985675|3757032.814275 -12523442.714250|5009377.085700 to a 8 x 8 tile
renderd[18553]: DEBUG: Got incoming connection, fd 9, number 2
renderd[18553]: DEBUG: Got incoming request with protocol version 2
renderd[18553]: DEBUG: Got command RenderLow fd(9) xml(tiles), z(8), x(47), y(103), mime(image/png), options()
renderd[18553]: DEBUG: Got incoming connection, fd 10, number 3
renderd[18553]: DEBUG: Got incoming request with protocol version 2
renderd[18553]: DEBUG: Got command RenderLow fd(10) xml(tiles), z(8), x(47), y(101), mime(image/png), options()
renderd[18553]: DEBUG: Got incoming connection, fd 11, number 4
renderd[18553]: DEBUG: Got incoming request with protocol version 2
renderd[18553]: DEBUG: Got command RenderLow fd(11) xml(tiles), z(8), x(47), y(102), mime(image/png), options()
renderd[18553]: DEBUG: Got incoming connection, fd 12, number 5
renderd[18553]: DEBUG: Got incoming request with protocol version 2
renderd[18553]: DEBUG: Got command RenderLow fd(12) xml(tiles), z(8), x(46), y(101), mime(image/png), options()
renderd[18553]: DEBUG: Got incoming connection, fd 14, number 6
renderd[18553]: DEBUG: Got incoming request with protocol version 2
renderd[18553]: DEBUG: Got command RenderLow fd(14) xml(tiles), z(8), x(46), y(102), mime(image/png), options()

If I stop the renderd process, the tiles are pulled from cache instantly, but if it is running it queries the DB even when it doesn't need to. I tried increasing the minimum cache, the render_list was run last week, so if that time listed is in seconds then the cache would last 28 years, if it is in milliseconds it is only 10 days, but it has only been 5 days since render.

Here is my Apache Config:

    LoadTileConfigFile /usr/local/etc/renderd.conf
    ModTileRenderdSocketName /var/run/renderd/renderd.sock
    # Timeout before giving up for a tile to be rendered
    ModTileRequestTimeout 3
    # Timeout before giving up for a tile to be rendered that is otherwise missing
    ModTileMissingRequestTimeout 10
    ModTileCacheDurationMax 60480000000
    ModTileCacheDurationMinimum 908000000
    DocumentRoot /home/renderaccount/

And here is renderd:

[renderd]
num_threads=8
tile_dir=/home/renderaccount
stats_file=/var/run/renderd/renderd.stats

[mapnik]
plugins_dir=/usr/lib/mapnik/3.0/input
font_dir=/usr/share/fonts/truetype
font_dir_recurse=1

[tiles]
URI=/tiles/
TILEDIR=/home/renderaccount
XML=/home/renderaccount/openstreetmap-carto/mapnik.xml
HOST=*
TILESIZE=256
MAXZOOM=20

Any suggestions would be appreciated.

Accepted Answer

1

What I'd expect it to do is sending the current tile to the user, and rendering a new one in the background. The tile in your example is "age 5.93 days". If it was less than 4 days old I bet it wouldn't render a new one. It's zoom level 8, so I don't think that "dirty" will come into play.

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answered 22 Aug '18, 18:56

SomeoneElse ♦
36.9k●71●370●866
accept rate: 16%

The requests are low priority render request (RenderLow) which will be issued by mod_tile if the tile is considered "old but not too old". A tile starts becoming old when its timestamp is older than the timestamp of the planet-import-complete file at the root of the tile directory. If such a file does not exist, the tile starts becoming old when its timestamp is older than three days (https://github.com/openstreetmap/mod_tile/blob/62c4a5ac7a57720182125b8aad11929dae947e46/src/store_file.c#L40-L41). To avoid re-rendering of old tiles altogether, provide a planet-import-complete file that has a very old timestamp. To allow re-rendering but not have the client wait for such tiles, set your ModTileRequestTimeout to 0 instead of 3.

(22 Aug '18, 19:08) Frederik Ramm ♦

Thank you Frederik, that worked perfect.

(23 Aug '18, 19:13) AlanHalls

Mod_Tile handing off to renderd when tiles exist

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