This package implements serverless parallelism on Azure (Azure batch) for JUDI using AzureClusterlessHPC.

To install this package simply run the standard command

] add https://github.com/slimgroup/JUDI4Cloud.jl

Note The default docker container used is based on julia v1.7. Since the communication with Azure Blob is done through Serialization, it is mandatory to use the same version of Julia locally. If you use the default container, use Julia v1.7, and if you use your own container make sure to have compatible Julia versions.

Following AzureClusterlessHPC convention, we rely on a remote runtime docker container with all the necessary packages installed and the runtime version of AzureClusterlessHPC installed. For convenience, we provide a docker container with the latest version of AzureClusterlessHPC, [JUDI4Cloud] and JUDI installed for Julia 1.6 or 1.7. These images are named mloubout/judi4cloud:1.6 and mloubout/judi4cloud:1.7. This image contains additional SLIM packages as well such as SegyIO if the user were to need it.

Additionally, these two premade images provide the Nvidia HPC SDK to enable GPU accceleration of the propagators. You can therefore use GPU instances as well. Enabling GPU can be done by specifying gpu=true when initializing the batch pool.

To use this package, simply replace using JUDI by using JUDI4Cloud at the top of your script. All JUDI functionalities are reexported to make your script compatible.

Once JUDI4Cloud is imported, you can use its main functionality to start an Azure batch pool to use as your serverless remote task farm. To start a batch pool with 2 nodes and 4 threads per node run:

nworkers = 2
init_culsterless(nworkers; credentials=creds, vm_size="Standard_E2s_v3", pool_name="PoolTest", verbose=1, nthreads=4)

where:

• creds is the path to your credentials JSON file (see credentials for information)
• vm_size is the Azure VM you want to use. This VM needs to be available in your batch account
• pool_name is the of the batch pool of nodes
• verbose controls AzureClusterlessHPC's verbosity
• nthreads defines the number of OpenMP threads to use on each node
• gpu whether to use (Nvidia) gpu for the propagators via openacc. You will need to specify a GPU VM.

A simple example is available at examples/modeling_basic_2D.jl. This example is a verbatim copy of the corresponding JUDI example, with the exception of the Azure setup at the top, and shows the seamless usability of this package.

The following extensions are currently in development:

• Parallel Julia on each node.
• More flexibility to switch between conventional Julia parallelism and Azure
• Out of core judiVector with Blob storage

This software is developed at Georgia Institute of Technology as part of the ML4Seismic consortium. For questions or issues, please open an issue on GitHub or contact the author:

• Mathias Louboutin: mlouboutin3@gatech.edu