just wanted to give a brief update on this. The problem was in fact that
we did not correctly move the shared file pointer to the end of the file
when a file is opened in append mode. (The individual file pointer did
the right thing however). The patch itself is not overly complected, I
filed a pr towards masters, and will create pr for the 2.0 and 2.1
release later as well. I am not sure however whether it will make it in
time for the 2.0.2 release, it might be too late for that.
Thanks for the bug report!
Edgar
On 1/18/2017 9:36 AM, Nicolas Joly wrote:
Hi,
We have a tool where all workers will use MPI_File_write_shared() on a
file that was opened with MPI_MODE_APPEND, mostly because rank 0 will
have written some format specific header data.
We recently upgraded our openmpi version from v1.10.4 to v2.0.1. And
at that time we noticed a behaviour change ... ompio do not show the
same result as romio with the attached code.
njoly@tars-submit0 [tmp/mpiio]> mpirun --version
mpirun (Open MPI) 2.0.1
[...]
njoly@tars-submit0 [tmp/mpiio]> mpirun -n 1 --mca io romio314 ./openappend
njoly@tars-submit0 [tmp/mpiio]> echo $?
0
njoly@tars-submit0 [tmp/mpiio]> cat openappend.test
Header line
Data line
njoly@tars-submit0 [tmp/mpiio]> mpirun -n 1 --mca io ompio ./openappend
njoly@tars-submit0 [tmp/mpiio]> echo $?
0
njoly@tars-submit0 [tmp/mpiio]> cat openappend.test
Data line
e
With ompio, it seems that, for some reason, the shared file pointer
was reset/initialised(?) to zero ... leading to an unexpected write
position for the "Data line" buffer.
Thanks in advance.
Regards.
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