[gradsusr] Speed optimizations

[James T. Potemra]

Hi Travis,

This seems a little strange to me.  I did a quick test with one of our 
higher res data sets (global bathy) that is 21600 by 64800 (x,y) and it 
loads almost instantly in GrADS.  Of course generating a display takes a 
long time, and my test was done on a netCDF file.

This aside, could you run the data through an OPeNDAP server?  Even 
though it would be on the same machine, you could use the server to 
subset via the DAP call, rather than relying on GrADS to load the entire 
file.

Jim

On 1/14/16 12:54 PM, Travis Wilson - NOAA Federal wrote:
>
> Hi,
>
>
> At the NWS we have been using grads to create images from grib files 
> on the fly.  Users use a front end interface to select a model (which 
> is just a grib file on a server), field, and view, and submits a job.  
> Within 3-4 seconds the server is able to launch grads, open the grib 
> file, and produce 50-100 images for the user to view.  This works 
> extremely well for CONUS datasets with medium to coarse resolutions 
> (up to 6km).
>
> We have started using higher resolution grib files (1 km radar files 
> are attached) and they are substantially slower.  The main problem 
> comes from opening the file.  If a user selects radar for Northern 
> California, it takes grads approximately 18 seconds just to open the 
> 1km CONUS radar file (scanning descriptor file)..and then grads plots 
> rather quickly.
>
>
> A workaround we have been using is to subset the data on the fly 
> (since we don’t know the area the user will select).  This example 
> regrids the CONUS radar for northern California.
>
>
> wgrib2 1kmradar_201512241600.grib2 -small_grib 233:243 36.8:42.8 
> 1kmradar_201512241600.grib2.small
>
>
> The small grib file will open in GrADS in about 1 second.  Regridding, 
> and remaking the ctl and idx is substantially faster, but still 
> requires a lot of time.  My question is, is there any way to speed up 
> the scanning of the CONUS descriptor file without subset the grib 
> file.  For example, grads would not scan the entire conus descriptor 
> file when we just need to look at Northern California (or whatever 
> portion of the US the users selects).
>
>
> We appreciate all the help,
>
> Travis
>
>
>
> _______________________________________________
> gradsusr mailing list
> gradsusr at gradsusr.org
> http://gradsusr.org/mailman/listinfo/gradsusr

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://gradsusr.org/pipermail/gradsusr/attachments/20160114/2f8d5856/attachment.html