Week 9

Assignment 4: Dining Java Philosophers

• Assigned: Mon, Oct 19
• Due: Fri, Oct 30
• PDF
• Questions?

Notes

• Ben-Ari slides: PDF
• My monitor notes: PDF
• Monitor state transition diagram: PDF
  
  

Class participation with monitors:

• The One-Lane Bridge problem:

  Cars coming from the north and south arrive at a 
  one-lane bridge. Cars heading in the same direction 
  can cross the bridge at the same time, but cars 
  heading in opposite directions cannot.

• can we find a way to be safe, fair, and efficient?
• handout: PDF (with thanks to Charlie Hughes!)

• CSP and Go!
• Hoare's 1978 CSP paper: https://spinroot.com/courses/summer/Papers/hoare_1978.pdf
  • Go implementation of examples from paper: https://godoc.org/github.com/thomas11/csp
• Rob Pike's Google I/O 2012 - Go Concurrency Patterns: https://youtu.be/f6kdp27TYZs
• Peter Welch's slides introducing CSP and occam-pi (but we will use Go this semester!)
  • Occam-pi Lecture Notes
  • even though we won't be programming in occam-pi, I want to give you a flavor of it
  • because:
    • ultimate lightweight processes!
    • composition!
  • Objects Considered Harmful (slide 27 of motivation.pdf slides)
  • Legoland: (slide 83-end of basics.pdf)
    
    

• Demo and codewalk of csp-dining-philosophers.go
  • Go language features highlighted:
    • channels
    • select
  • Design basis for solution in Go: go routines (processes)
    • room (communicates with philosophers over channels)
      • for philosophers to enter/leave – at most 4 at a time to prevent deadlocking, 5th philosopher blocks
    • forks (communicate with philosophers over channels)
    • philosophers (communicate with forks over channels)