Re: [netcdf-hdf] [netcdfgroup] netcdf4 and OpenMP

  • To: Ed Hartnett <ed@xxxxxxxxxxxxxxxx>
  • Subject: Re: [netcdf-hdf] [netcdfgroup] netcdf4 and OpenMP
  • From: Charlie Zender <zender@xxxxxxx>
  • Date: Fri, 23 May 2008 00:52:16 +0200

Neither netcdf-3 nor netcdf-4 are known to be threadsafe. But the
reason you are not seeing this is that you are probably only doing
reads (and writes?) of data, and not any metadata operations.

Yes. we thread the data and (some) metadata reads. All the writes are
done single-threaded or in "critical regions", i.e., restricted to
one thread at a time. This avoids all the gotchas we know of.
It's the unknown unknowns that we're less sure about :)
Will think more about Ed's record variable example.
Makes my head hurt.

Charlie Zender, Department of Earth System Science, UC Irvine
Sab. at CNRS/LGGE-Grenoble until 20080815 :) 011+33+476+824236
Laboratoire de Glaciologie et Géophysique de l'Environnement
54 rue Molière BP 96, 38402 Saint Martin d'Hères Cedex, France