Due to the current gap in continued funding from the U.S. National Science Foundation (NSF), the NSF Unidata Program Center has temporarily paused most operations. See NSF Unidata Pause in Most Operations for details.
Due to the current gap in continued funding from the U.S. National Science Foundation (NSF), the NSF Unidata Program Center has temporarily paused most operations. See NSF Unidata Pause in Most Operations for details.
So presumably if you use the NetCDF file cache, you have to do the synchronization yourself, since you might be transparently sharing file handles? That's an aspect of the cache that hadn't occurred to me before... Jon On Mon, Sep 15, 2008 at 8:23 PM, John Caron <caron@xxxxxxxxxxxxxxxx> wrote: > Hi Stuart: > > Underneath a Variable/NetcdfFile is (usually) a java.io.RandomAccessFile > object, which is not thread-safe, because it keeps the state of the file > position. So even if all you want to do is read data in multiple threads, you > need to synchronize, typically on the NetcdFile object. Alternatively, open a > new NetcdfFile for each thread. The Threads Data Server (TDS) uses a cache of > open NetcdfFile files by using the NetcdfFile.acquire() method, which allows > stateless handling of data requests minimizing file opening and closing.. > > > Stuart Maclean wrote: >> Is ucar.nc2.Variable intended to be thread safe, at least for >> Variables in 'read' mode?? If I do this: >> >> NetcdfFile nc = NetcdfFile.open( "foo.nc" ); >> Variable v = nc.findVariable( "v" ); >> >> then can I do calls like >> >> Array a = v.read( "section Spec" ); >> >> from many threads concurrently, with different sections obviously. >> >> Or is there state in a Variable that precludes this? I know I could >> trawl the source code but that is slow. >> >> Apologies if this is a FAQ > > No, but I need to start a FAQ and put this into it! > > John > _______________________________________________ > netcdf-java mailing list > netcdf-java@xxxxxxxxxxxxxxxx > For list information or to unsubscribe, visit: > http://www.unidata.ucar.edu/mailing_lists/ > -- Dr Jon Blower Technical Director, Reading e-Science Centre Environmental Systems Science Centre University of Reading Harry Pitt Building, 3 Earley Gate Reading RG6 6AL. UK Tel: +44 (0)118 378 5213 Fax: +44 (0)118 378 6413 j.d.blower@xxxxxxxxxxxxx http://www.nerc-essc.ac.uk/People/Staff/Blower_J.htm
netcdf-java archives: