DistributedImaging

WSClean can run in parallel on different nodes using openmp. To use this, you need a recent WSClean version, which provides the executable wsclean-mp.

A typical run:

mpirun --hostfile host_file -np 8 wsclean-mp -size 10000 10000 ...

And a host-file could look like this:

node100 slots=1
node116 slots=1
node118 slots=1
node119 slots=1
node122 slots=1
node123 slots=1
node124 slots=1
node125 slots=1
node126 slots=1
node127 slots=1
node128 slots=1
node129 slots=1
node130 slots=1

The host file should specify one slot per host, otherwise multiple wsclean's are executed on the same host, and that has (normally) no benefit, and would actually make those processes compete for memory and cpu. If you use wsclean-mp, all paths should be absolute for the hosts participating as well as reachable by all nodes (so -name should specify an absolute name, and the MSes should be absolute).

wsclean-mp will distribute the different channels to different nodes. This implies that if you don't use -channels-out there's no benefit, whereas using -channels-out 8 with -np 8 gives you a speed-up of 8. If multiple output channels are not necessary for your science goal, you can use -fit-spectral-pol 1 -deconvolution-channels 1.