On Fri, Feb 3, 2012 at 6:47 PM, Kytt MacManus
<[email protected]> wrote:
> Good afternoon,
>
> Could someone please explain the meaning of this message to me
>
>  "INFO [geoserver.catalog] - Disposing grid coverage reader"
>
>
> We are seeing this many times in the logs but aren't sure what it means
> or if it might be an issue.  Our GetCapabilities requests are slower
> than normal.

Not an issue per se, GeoServer keeps a cache of the readers to avoid
having to open and close them over and over, and the cache is limited to 100
items, every time you see one of those messages it means a new item
got into a full cache, meaning the oldest one gets purged.

On GeoServer trunk (what will become 2.2.x) we actually have a slightly
different arrangement, when the new item enters the cache the oldest
one is switched to a soft reference, that might be removed under memory
usage pressure, but not necessarily right away.

I looked into the caps generation process, on the stable series we have
the code actually grabbing the reader to see if it has any time/elevation
information attached.
On trunk this is not done unless you explicitly configure time and elevation,
but on 2.1.x this code makes GeoServer open each and every raster
for the sake of checking the presence of that metadata, so if you have
more than 100 distinct raster layers configured a GetCapabilities call
will basically end up opening them all, which is indeed a slow process.

Looking at the vector side I see a similar thing that makes the
code check the feature type for the presence of a geometry,
since geometryless layers cannot be published by WMS (but they
can be handled by WFS instead).
However for feature types we have a tunable "feature type cache"
size in the "global" configuration panel

Hum, I guess we could roll a similar configuration for raster data?
If you pump it up to a value higher than the number of layers the
slowness would be gone (btw, how many do you have?), provided
of course you have enough memory to keep all those readers
open at the same time.

Another easier fix would be to roll a system variable that just
disables the partial temporal support available on 2.1.x, so that
the readers are not going to be opened.

Cheers
Andrea

-- 
-------------------------------------------------------
Ing. Andrea Aime
GeoSolutions S.A.S.
Tech lead

Via Poggio alle Viti 1187
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