Re: [thredds] Large aggregated datasets, WMS memory issue

Hi Lin:

Its likely that you are at the edge of your heap memory, and "random" requests are pushing you over.

you might run a heap monitor like jvisualvm to watch the memory use.

a quick fix may be to reduce or eliminate file caching, eg:

    <*scour*>10 min</scour>

in threddsConfig.xml


if possible, run jvisualvm before and after any change to verify.

On 3/30/2011 6:25 PM, Xiangtan.Lin@xxxxxxxx wrote:
Hi John,
Thanks for the information. My large datasets will eventually be hosted on a 64bit JVM. At the moment, I'm testing a 1.3GB dataset with -Xmx1536m on a dev machine. The following WMS request results in HTTP Status 500 - Internal Server Error (java.lang.OutOfMemoryError: Java heap space): http://localhost:8090/thredds/wms/aggregated/,-39,154,-37&width=100&height=100&Styles=BOXFILL/occam_pastel-30&format=image/jpeg <http://localhost:8090/thredds/wms/aggregated/,-39,154,-37&width=100&height=100&Styles=BOXFILL/occam_pastel-30&format=image/jpeg>
The dataset has an bounding box:
** <eastBoundLongitude>*154.66376524558447*</eastBoundLongitude>
** **<southBoundLatitude>*-39.560232620003625*</southBoundLatitude>
** **<northBoundLatitude>*-35.19773436500001*</northBoundLatitude>
 I guess the request is faily small (BBOX=152,-39,154,-37) .
I In addtion, the NetCDFSubsetService works fine for the same dataset with the same amount of memory. I'm wondering if in general case, the maximum heap is determined by the dataset size for Thredds WMS service, and if there is an configuration option to limit the WMS request size.
Regards and thanks,
*From:* thredds-bounces@xxxxxxxxxxxxxxxx [mailto:thredds-bounces@xxxxxxxxxxxxxxxx] *On Behalf Of *John Caron
*Sent:* Thursday, 31 March 2011 5:21 AM
*To:* thredds@xxxxxxxxxxxxxxxx
*Subject:* Re: [thredds] Large aggregated datasets, WMS memory issue

Hi Lin:

It doesnt (usually) matter how big the dataset is, just how big the request is.

Can you send a typical WMS request that causes this problem? Do you know what size of data you are requesting? What file format?

-Xmx1536m is around the max for 32 bit JVMs. I strongly advise you to use a 64bit JVM with more like 4 Gbyte heap.


On 3/29/2011 7:19 PM, Xiangtan.Lin@xxxxxxxx wrote:
Hi all,
I'm in process of serving out some large aggregated datasets (5 - 8GB) with Thredds WMS. I consistently experience "OutOfMemoryError: Java heap space" error when making WMS requests. On my test machine, I've allocated -Xmx1536m to Tomcat and experimentally Thredds is able to serve about 1GB aggregated datasets. By digging through the Dataset Aggregation and Memory related topics on the list, I've found out that the general suggestions are to allocate more memory to Tomcat such as: -Xmx4g
One post mentioned that "Thredds does everything in memory".
Can somebody please advise how much memory I should allocate to Tomcat for the 8GB dataset? I'm afraid I have to secure more than 8GB memory. And what is the best practice to serve out the large datasets on Thredds in general?
Regards and thanks,


Technical Services Officer *|*CSIRO IM&T

*xiangtan.lin@xxxxxxxx* <mailto:xiangtan.lin@xxxxxxxx>*|*

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