OpenMPI 4 IO bug

[henry2004y]

I happen to have a minimal working example for reproducing the OpenMPI4 VLSV bug.

Here is a simple flowthrough test configuration file:

Flowthrough_1d_sin.cfg

project = Flowthrough
propagate_field = 0
propagate_vlasov_acceleration = 0
propagate_vlasov_translation = 1
dynamic_timestep = 1

ParticlePopulations = proton

[io]
write_initial_state = 0

system_write_t_interval = 20.0
system_write_file_name = bulk
system_write_distribution_stride = 0
system_write_distribution_xline_stride = 1
system_write_distribution_yline_stride = 0
system_write_distribution_zline_stride = 0

[variables]
output = populations_vg_v
output = populations_vg_rho
diagnostic = populations_vg_blocks

[gridbuilder]
x_length = 10
y_length = 1
z_length = 1
x_min = -10.
x_max = 10.
y_min = -1.0
y_max = 1.0
z_min = -1.0
z_max = 1.0
t_max = 20.0
dt = 0.00625

[proton_properties]
mass = 1
mass_units = PROTON
charge = 1

[proton_vspace]
vx_min = +0.5
vx_max = +1.5
vy_min = -1.0
vy_max = +1.0
vz_min = -1.0
vz_max = +1.0
vx_length = 160
vy_length = 10
vz_length = 10

[proton_sparse]
minValue = -1.0e-20

[boundaries]
periodic_x = yes
periodic_y = yes
periodic_z = yes

[Flowthrough]
densityModel = Sinewave
densityWidth = 10.0
Bx = 1e-9
By = 0e-9
Bz = 0e-9

[proton_Flowthrough]
T = 1.0e-7
rho = 0.5
rhoBase = 0.25
VX0 = 1.0
VY0 = 0
VZ0 = 0
nSpaceSamples = 1
nVelocitySamples = 1

[bailout]
velocity_space_wall_block_margin = 0

When system_write_distribution_stride = 0, then the output VLSV files are good. However, when system_write_distribution_stride = 1, the output VLSV files lose the metadata at the end.

The current workaround is to disable OpenMPI’s I/O implementation, export OMPI_MCA_io=^ompio.

[markusbattarbee]

This is now handled by the code in #800