Communicator

eOn has a server client architecture for running its calculations. The simulation data is stored on the server and clients are sent jobs and return the results. Each time eOn is run it first checks to see if any results have come back from clients and processes them accordingly and then submits more jobs if needed. In eOn there are several different ways to run jobs. One can run them locally on the server, via MPI, or using a job queuing system such as SGE.

Note

As of version 2.0 onwards, we recommend using dedicated workflow management tools (like AiiDA or Snakemake or Fireworks) instead of using eOn to generate submission scripts.

Configuration

[Communicator]

Examples

An example communicator section using the local communicator with an Eon client binary named eonclient-custom that either exists in the $PATH or in the same directory as the configuration file and uses makes use of 8 CPUs.

[Communicator]
type = "local"
client_path = "eonclient-custom"
number_of_cpus = 8

Additional Topics

Changed in version 2.0: Potentials which can be run in parallel, like those accessed through ASE (e.g. ORCA) are always run in parallel, for the others, there is little to no benefit for this additional overhead.

MPI

Warning

Not tested on 2.0, only ever supported AKMC.

The MPI communicator allows for the server and client to be run as a MPI job. The number of clients that are run and thus the number of jobs is set at runtime by the MPI environment.

A MPI aware client must be compiled, which will be named eonclientmpi instead of eonclient. It can only be used to run MPI jobs.

To run EON with MPI, two environment variables must be set. The variable EON_NUMBER_OF_CLIENTS determines how many of the ranks should become clients and EON_SERVER_PATH is the path to the server Python script. In MPI mode the clients need to be started instead of the server and one of them will become the server process. Currently only AKMC is supported. Below is an example of running using the MPI communicator:

#!/bin/bash
export EON_NUMBER_OF_CLIENTS=7
export EON_SERVER_PATH=~/eon/akmc.py
mpirun -n 8 ~/eon/client/eonclientmpi

Cluster

Warning

Not tested on 2.0

An example communicator section for the cluster communicator using the provided sge6.2 scripts and a name prefix of al_diffusion_:

[Communicator]
type = "cluster"
name_prefix = "al_diffusion_"
script_path = "/home/user/eon/tools/clusters/sge6.2"