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NOTICE: This version of the NSF Unidata web site (archive.unidata.ucar.edu) is no longer being updated.
Current content can be found at unidata.ucar.edu.
To learn about what's going on, see About the Archive Site.
Michael,
> From: "Plonski, Michael" <mplonski@xxxxxxx>
> To: "'John Caron'" <caron@xxxxxxxxxxxxxxxx>
> Cc: <mplonski@xxxxxxx>
> Sent: Saturday, September 15, 2001 11:30 AM
> Subject: RE: netcdf and multiarray directories in Netcdf ver 2 .vs. Ver 1
The above message contained the following:
> > I haven't tried it yet because I am about to give up with VisAD.
> > I thought if I got it to read netCDF better (read pieces of large
> > files), it would be more useful to me. I have some home grown netcdf
> > files that are typically in the several hundred Mb range with X,y
> > dimensions in the order of 2000 x 1500 and then some meteorological data
> > with bands and other with levels. Even running VisAD with something
> > like -mx800m, it still just croaks on things. I was trying to modify
> > the ingest so that I could just read a few netcdf variables at a time
> > using your version 2 netcdf. I wrote up some code that just lets me
> > extract one variable at a time from the file, without using the visad
> > "plain". Plain() reads the whole files and just croaks on my data
> > files at the start. The problem is there seems to be some memory leaks
> > in VIsad and even after you get the data in, memory still seems to go up
> > way too high and things really run slow. I am surprised how slow visad
> > runs on a Sun Ultra 60 - it seems to do much better on a Pentium 4.
You can reduce memory-usage by telling the netCDF-import
module to maximize the number of VisAD FileFlatField-s
used to represent the data. This is done by setting
the Java property "visad.data.netcdf.in.Strategy" to
"visad.data.netcdf.in.MaxFileFieldStrategy". For example:
$ java
-Dvisad.data.netcdf.in.Strategy=visad.data.netcdf.in.MaxFileFieldStrategy ...
Additionally, a version of VisAD which should be released soon will have
the ability to import an arbitray subset of the parameters in a local
netCDF file.
Regards,
Steve Emmerson <http://www.unidata.ucar.edu>
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