Bill Moninger wrote:
Hi Robb,
thanks for the information. I'll take a look at regenerating the gbx
files.
For what its worth--the *biggest* percentage slowdown is not with grib
or grib2 files, but with netCDF files, surprisingly enough. My c
routine (using an earlier version of netCDF) reads the files almost
instantly--the java-netcdf4 arrangement reads the file much more slowly.
Thats interesting. When you say "read" do you mean read all the data, or
just opening the file? I assume netcdf 3 formatted files?
Can you send a sample program that has this slowdown? Are you comparing
against a C program or earlier versions of java-netcdf?
BTW, java 1.6 should be 20-30% faster than java 1.5, particularly if you
use the -server option.
-Bill
On 3/31/2009 12:56 PM, Robb Kambic wrote:
On Fri, 27 Mar 2009, Bill Moninger wrote:
Hello netcdf-java folks,
Thanks to good help from the netcdf-java staff, I'm now able to read
and generate soundings from RUC files in netCDF, grib, and grib2
format. Its really nice to be able to use the same code for all
three formats.
Unfortunately, I find that, at least as I've implemented it,
netcdf-java is 20% to 50% slower than my previous methods (using C).
Bill,
If you use the the grib index file, those are the files with the gbx
suffix that are usually in the same dir as the grib file. You should
delete them all and then regenerate them. The new index file read in
much quicker. Currently, i working on grib performance issues
Robb...
Moreover, it appears that java 1.6 is slower than 1.5 (though I
haven't recompiled the underlying UCAR code in 1.6--only my code).
If folks have any thoughts about how to speed things up, I will be
much obliged to hear them.
-Bill
--
William R. Moninger http://www-frd.fsl.noaa.gov/~moninger/
NOAA / Earth Systems Research Laboratory / Global Systems Division
325 Broadway, R/GSD1 voice: 303-497-6435
Boulder, CO 80305 fax: 303-497-3329
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Robb Kambic Unidata Program Center
Software Engineer III Univ. Corp for Atmospheric Research
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