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Programming Paradigms - Lecture 15

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Lecture 15 - Concurrent Programming, Semaphore

Transitioning from Sequential Programming to Concurrent Programming in the Ticket Sale Example, Problems with the Sequential Model, Threading Interface, Rewriting the Ticket Example to Use It, Adding a Randomized Threadsleep Call to the Threads to Make the Time Slices Used by the Different Threads Less Uniform, Sample Output of Our Ticket Threads, How a Thread Can be Interrupted in the Middle of a Nonatomic Operation, How Multithreading Can Drastically Speed Up the RSS News Reader by Allowing Some Feeds to be Loaded While the Other Feeds Are Blocked, Allowing Each of the Ticket Threads to Access A Global Pool of Tickets, Rather than Allocating 15 Tickets to Each Agent, How This Can Lead to Problems When Threads Attempt to Access the Shared Data Simultaneously, How We Can Prevent This from Happening By Enclosing the Critical Region within A Semaphore, the Semaphorewait And Semaphoresignal Functions, Modifying the Selltickets Function to Use the Semaphore to Protect the Shared Data, How Changing the initial Value of the Semaphore Can Create Deadlock or Allow Too Many Threads to Access the Shared Data At Once

Prof. Jerry Cain
CS107 Programming Paradigms
(Stanford University: Stanford Engineering Everywhere)
http://see.stanford.edu
Date accessed: 2009-05-09
License: Creative Commons Attribution 3.0

Lecture Material

Supplementary lecture material is listed below.

1. Thread Package Docs
2. Concurrency Examples



 

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