On the topic of caching opened files (external or otherwise), I have a
question.

In VisIt, we have many different 'flavors' of HDF5 files we read. A
'flavor' is a particular structure (groups/dataset/attribute names) of
HDF5 file. We have a separate reader plugin for each flavor.

We don't always know ahead of time which plugin should be used to open a
given HDF5 file. So, we can wind up iterating over several, each
attempting some HDF5 operations on the file and, perhaps, throwing
exceptions (VisIt exceptions not HDF5 exceptions) and then moving onto
the next HDF5 reader plugin to try.

Here is my question. If one reader plugin calls H5Fopen and that
succeeds but later in the plugin's attempt to read the file, it throws a
VisIt exception to move onto the next plugin, what if it also does NOT
call H5Fclose? Will that potentially negatively affect the next reader
plugin which will also use H5Fopen to open that same file? Also, how
does fact that these plugins are operating as shared libs effect things,
in particular, any HDF5 library wide global data such as the list of
cached files it has open?

Mark

On Mon, 2010-11-08 at 07:05, Quincey Koziol wrote:
> Hi all,
>       I've post a new RFC describing a feature we are planning to add to the 
> HDF5 library that will cache open files from external links:
> 
> http://BLOCKEDwww.BLOCKEDhdfgroup.uiuc.edu/RFC/HDF5/ExternalLinkFileAccessProperty/CacheExternalLinkFileOpens.pdf
> 
>       If you are using external links and would like to comment on this 
> performance enhancement, please do so.
> 
>       Thanks,
>               Quincey
> 
> 
> _______________________________________________
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-- 
Mark C. Miller, Lawrence Livermore National Laboratory
================!!LLNL BUSINESS ONLY!!================
[email protected]      urgent: [email protected]
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