Summary

This lesson summarizes the chapter on event-based concurrency with some concluding remarks.

We’ve presented a bare-bones introduction to a different style of concurrency based on events. Event-based servers give control of scheduling to the application itself but do so at some cost in complexity and difficulty of integration with other aspects of modern systems (e.g., paging). Because of these challenges, no single approach has emerged as best. Thus, both threads and events are likely to persist as two different approaches to the same concurrency problem for many years to come. Read some research papers1- “Cooperative Task Management Without Manual Stack Management” by Atul Adya, Jon Howell, Marvin Theimer, William J. Bolosky, John R. Douceur. USENIX ATC ’02, Monterey, CA, June 2002. This gem of a paper is the first to clearly articulate some of the difficulties of event-based concurrency, and suggests some simple solutions, as well explores the even crazier idea of combining the two types of concurrency management into a single application! 2- “Flash: An Efficient and Portable Web Server” by Vivek S. Pai, Peter Druschel, Willy Zwaenepoel. USENIX ’99, Monterey, CA, June 1999. A pioneering paper on how to structure web servers in the then-burgeoning Internet era. Read it to understand the basics as well as to see the authors’ ideas on how to build hybrids when support for asynchronous I/O is lacking. 3- “Capriccio: Scalable Threads for Internet Services” by Rob von Behren, Jeremy Condit, Feng Zhou, George C. Necula, Eric Brewer. SOSP ’03, Lake George, New York, October 2003. A paper about how to make threads work at extreme scale; a counter to all the event-based work ongoing at the time. 4- “Capriccio: Scalable Threads for Internet Services” by Rob von Behren, Jeremy Condit, Feng Zhou, George C. Necula, Eric Brewer. SOSP ’03, Lake George, New York, October 2003. A paper about how to make threads work at extreme scale; a counter to all the event-based work ongoing at the time. or better yet, write some event-based code, to learn more.

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