Fortran

In this section, we’ll build from our tsunami teams example and use events to post updates from the simulation team to the logging team about data being written to disk. While this is technically doable with coarrays alone, you’ll see that events are a perfect candidate for such parallel patterns. Before we jump back into […]

In the previous section, we used teams to distribute work among groups of images. Teams allow us to express some parallel patterns and synchronization more elegantly than we otherwise could by controlling individual images directly. Fortran 2018 introduces another new parallel concept called events, provided through the built-in derived type called event_type. In a nutshell, you can post […]

We’ve learned so far, both from coarrays in chapter 7 and from developing the parallel tsunami simulator, that synchronizing images is crucial for writing correct parallel programs. Recall that when we have data dependency between parallel images, one image must wait for data from another image before proceeding with its own calculation. This subsection explains […]

Now that we have two new teams, how do we instruct images on each team to do certain kinds of work? Recall that by default, all images start on the same team. We need to switch each image to a new team to get it to work on a different task. We do this with the change team construct. […]

Before we dive into the implementation of teams in the tsunami simulator, let’s look at the syntax of forming new teams, which will apply to any parallel program that uses them. In the beginning of the program, there’s only one team, and we’ll refer to it as the initial team. All images that run the program […]

In this section, we’ll use teams to augment our tsunami simulator and assign different roles to parallel images working concurrently. For brevity and to not get bogged down in the details of what the specific roles could be in real-world simulation software, we’ll create only two teams: the compute team and the logging team. While […]

Fortran 2018 introduced teams to allow the programmer to assign different tasks to groups of images. For example, if you’re computing a weather simulation on 16 images, you could assign them different roles (figure 12.1). Figure 12.1 A weather model workflow, with parallel images distributed in different teams and each box with a number in […]

Chapter 7 introduced the parallel programming concepts in Fortran, including images, synchronization, and data exchange using coarrays. I strongly recommend that you read that chapter before starting this one. Nevertheless, let’s refresh our memory on these concepts before we build further on them. Fortran refers to any parallel process as an image. Under the hood, an […]