ygm::comm class reference.

Communicator Overview

The communicator ygm::comm is the central object in YGM. The communicator controls an interface to an MPI communicator, and its functionality can be modified by additional optional parameters.

Communicator Features:

  • Message Buffering - Increases application throughput at the expense of increased message latency.

  • Message Routing - Extends benefits of message buffering to extremely large HPC allocations.

  • Fire-and-Forget RPC Semantics - A sender provides the function and function arguments for execution on a specified destination rank through an async call. This function will complete on the destination rank at an unspecified time in the future, but YGM does not explicitly make the sender aware of this completion.

Communicator Hello World

Here we will walk through a basic “hello world” YGM program. The examples directory in the YGM tutorial contains several other examples, including many using YGM’s storage containers.

To begin, headers for a YGM communicator are needed:

#include <ygm/comm.hpp>

At the beginning of the program, a YGM communicator must be constructed. It will be given argc and argv like MPI_Init.

ygm::comm world(&argc, &argv);

Next, we need a lambda to send through YGM. We’ll do a simple hello_world type of lambda.

auto hello_world_lambda = [](const std::string &name) {
        std::cout << "Hello " << name << std::endl;
};

Finally, we use this lambda inside of our async calls. In this case, we will have rank 0 send a message to rank 1, telling it to greet the world

if (world.rank0()) {
        world.async(1, hello_world_lambda, std::string("world"));
}

A full, compilable version of this example is found here.

Communicator API