Hi,
I am using netcdf in a threaded C program. I found that when I use more
than 1 thread an assert in POSIX I/O routine fails
posixio.c:376: px_rel: Assertion `pxp->bf_offset <= offset && offset
< pxp->bf_offset + (off_t) pxp->bf_extent' failed.
this lead me to the FAQ which explains that nstcdf is not thread safe. I
have a few questions below about what is the best approach to use netcdf
in a threaded program.
Here are some details about my use case. the files are in classic format
(not hdf5). The access to the files is read only. Each file contains a
number of time steps. in my code time steps are assigned to threads for
processing in parallel. each thread may read and process a number of
variables from a given time step before moving on to another time step.
the threads are sharing the file handles, to avoid having to re-open the
same file multiple times.
Do I need to lock every netcdf call ?
when a thread will read a list of variables in a loop, is it better to
have the lock outside the loop, or just around the read call ?
Should file handles be local to a thread, or is sharing them more
efficient ?
Thanks
Burlen
