Hi Andrea,
It is really a snapshot of 2.8, build date 2015-Oct-08.
I wonder what it would help to write the output with FILE strategy. The output tiff is technically correct with 24000x24000 pixels. The problem is that is contains 25%, 50%, or 75% black pixels because of the heap memory error that occurred while reading the input data from the mosaic.
You wrote that after your change the whole source layer is loaded into memory. Obviously you do not mean the whole layer, though, but the requested area + some extra pixels which come for example from tiled tiffs? At least I can serve small parts of a DEM that is 8 GB as a single tiff file with the same snapshot version and for sure there is not that much memory for Java.
If you read the whole source data first into memory, can’t you wait and see if it really fits into memory before starting to write out the tiff file?
Am I right that the amount of free java memory and the amount of data that is read from the source data sets the limits for the WCS? With the default policy “Don’t use overviews” of if there are no overviews the maximum subset for one coverage is always the same independently of the output resolution because it is the amount of input data that sets the limit, not the size of the generated output? With 1 m resolution you can get more data out of WCS in megabytes than with 20 m resolution, but the limit in square km is constant?
-Jukka Rahkonen-
Andrea Aime wrote:
···
Hi Jukka,
I’ve recently fixed an issue in WCS that prevented streaming, and made the
code load the whole source layer in memory.
Are you using recent nightly builds?
About the lack of error message, not sure what to say about it, if we started
writing the tiff already there is no way to take it back and return a proper error
message but you can configure the service strategy to “file”, that might help:
http://docs.geoserver.org/2.7.0/user/production/config.html#set-a-service-strategy
Cheers
Andrea
On Fri, Nov 6, 2015 at 1:42 PM, Rahkonen Jukka (MML) <jukka.rahkonen@…6847…> wrote:
Hi,
I have tried to find out why WCS GetCoverage from an image mosaic layer seems to be successful without errors but when I open the resulting GeoTIFF it is missing data. My request it hitting four granules in the mosaic and depending on my settings the GeoTIFF has either 1, 2, or three quarters filled with all black.
Now it seems to me that my Geoserver is meeting the heap memory limit while it is trying to add some granules from the mosaic. That’s OK, but instead of sending an exception Geoserver just continues with processing the GetCoverage request and finally it sends out a GeoTIFF that contains data from those granules it did manage to read without heap memory issue.
Log from one GetCoverage request attached. It has two heap space errors on lines 162 and 451.
ReadType=DIRECT_READ Resulting in no granule loaded: Empty result
java.lang.OutOfMemoryError: Java heap spaceIf my analysis is right wouldn’t it be better to catch the first OutOfMemoryError and send an exception?
-Jukka Rahkonen-
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