Lecture 7: Concurrency

Title slideMoving on from type systems, today’s lecture started a look at programming for concurrency: why you might want — or need — to write concurrent code and some of the challenges in doing so. I also introduced some of the concurrency primitives in Java and how they are used, as well as telling a story about the Apollo Guidance Computer and the robustness of its concurrent event handling under input overload.

Link: Slides for Lecture 7

Homework

Do this

Find out what a data race is. What happens to C or C++ code that contains a data race?

Read this

Work through the first three sections of the Java Concurrency Tutorial.

Look for other tutorials on Java concurrency — there are many. Post links for ones you like to the apl-students@inf.ed.ac.uk mailing list.

References

Quite a lot this time. I used the following pieces as sources for some of the images and ideas in the lecture slides.

The first article identified the impact of hardware trends on the need for concurrent programming; the follow-up a few years later goes into great detail on just how extensive that is and the wide range of concurrency that’s involved.

These contrasting talks argue for and against threads or events being a good model for programming concurrent systems.

Margaret Hamilton is a software engineer who was lead developer for the Apollo flight software. The following fairly sedate NASA announcement and rather more effusive magazine articles describe some of her achievements in a lifetime of professional computing.

Code for the Apollo Guidance Computer written by Hamilton’s team is now on GitHub.

You can also run it in a web page, a stand-alone emulator, or to fly a virtual spacecraft (some assembly required).

After the Women of NASA proposal reached 10k votes in two weeks earlier this year, LEGO have passed it to their official Review Board and in due course may be making that Margaret Hamilton minifig.

LEGO minifig of Margaret Hamilton standing beside AGC code LEGO proposed Women of NASA set
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