1. CS533 Concepts of Operating Systems Class 7
Event-Based Systems

2. CS533 - Concepts of Operating Systems
Questions
How does event-based programming relate to interrupt handling?
Where is the boundary between interrupt handling and scheduled thread execution?
What are the implications of mixing these models?
CS533 - Concepts of Operating Systems

3. CS533 - Concepts of Operating Systems
Questions
How can resources be scheduled in event-based programming?
What is the problem with event handlers blocking or performing long-lived computation?
CS533 - Concepts of Operating Systems

4. CS533 - Concepts of Operating Systems
Questions
What is the problem with making resource allocation decisions statically?
What is the Slashdot effect?
Why is massive concurrency not a good match for multi-threading?
Is web service embarrassingly parallel?
What transparency is imposed (ie., what is hidden?) by the thread-per request model?
Why does it hurt?
Why does the event handling model help?
CS533 - Concepts of Operating Systems

5. CS533 - Concepts of Operating Systems
Questions
What is a thread pool?
Why do the following techniques help during heavy load?
Thread pool resizing
Event batching
Adaptive load shedding
Why does pipeline parallelism scale well?
Thread per stage vs thread per request
What does it mean for a service to be “well conditioned”?
CS533 - Concepts of Operating Systems

6. CS533 - Concepts of Operating Systems
Questions
Do Ousterhout and Welsh contradict each other?
What is hard about programming threads?
What is easy about programming threads?
What is hard about programming events?
What is easy about programming events?
CS533 - Concepts of Operating Systems

7. CS533 - Concepts of Operating Systems
Reminder
Class 8 presenters
Discuss your presentation plans with me ahead of time
Mail me the final version of your slides BEFORE the class
CS533 - Concepts of Operating Systems