Hi Andrew,

Since it’s going to be hard to replicate this, could you provide more 
information by attaching a debugger and show the trace of where the hang is?

Thanks,
Mohamad

From: Hdf-forum <[email protected]> on behalf of Andrew Ho 
<[email protected]>
Reply-To: hdf-forum <[email protected]>
Date: Friday, June 10, 2016 at 10:06 PM
To: hdf-forum <[email protected]>
Subject: [Hdf-forum] Parallel HDF5 file locking error

I'm having some issues with file locking on a parallel filesystem which I 
believe is related the problem here: 
https://lists.hdfgroup.org/pipermail/hdf-forum_lists.hdfgroup.org/2011-February/004254.html

I tried the suggestion of disabling romio_ds_read and romio_ds_write, but this 
doesn't fix the problem. I've also tried setting H5Pset_seive_buf_size to 0 to 
disable data striding in HDF5 itself, but that doesn't work, either.

Here's a short snippet of the relevant code:

hid_t fapl_id = H5Pcreate(H5P_FILE_ACCESS);
MPI_Info info;
MPI_Info_create(&info);
MPI_Info_set(info, "romio_ds_read", "disable");
MPI_Info_set(info, "romio_ds_write", "disable");
H5Pset_sieve_buf_size(fapl_id, 0);
H5Pset_fapl_mpio(fapl_id, comm, info);

hid_t f_id = H5Fcreate("test_file.h5", H5F_ACC_TRUNC, H5P_DEFAULT, fapl_id);

It's on this last line that the program hangs, and eventually MPI_ABORT gets 
called. Note that I get the same problem regardless of if I try to create a new 
file, or if I try to open an existing file:

hid_t f_id = H5Fopen("test_file.h5", H5F_ACC_RDWR, fapl_id);

Other relevant information:

1. Filesystem is NFS v3 with noac off (can't change)
2. Tested with HDF 5.8.13 and 5.8.14
3. Tested with OpenMPI 1.6.5 and 1.10.2

What am I missing? I saw that there's an option to disable filesystem 
atomicity, but this requires that the file already be opened, and I can't even 
get that far.

I also know that my code does work on different computers with different 
filesystems and/or mount options.
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