What I Teach (Do what I say, not what I do)

What I Teach(Do what I say, not what I do) Andrew Lumsdaine Indiana University

B524: Parallelism in Programming Languages and Systems Andrew Lumsdaine Computer Science Department Indiana University Bloomington, IN 47401

Course Text • Andrews, “Foundations of Multithreaded, Parallel, and Distributed Programming”

Supplemental Text • Schneider, “On Concurrent Programming”

Supplemental Texts • Andrews, Concurrent Programming

Course Outline • Introduction / overview • Program logic • Semantics of concurrency • Safety properties • Fine grained atomicity • Semaphores, locks, etc • Message passing • Case studies

{P Λ B} S {Q} {Pi} Si {Qi} are interference free {P} < await (B) S;> {Q} {P1 Λ P2 Λ … Pn} Co S1 ; // S2 … // Sn; oc {Q1 Λ Q2 Λ … Qn} Semantics of Concurrent Execution • Await Rule • Co Rule

Critical Section Problem sem mutex = 1; process CS[i = 1 to n] { while (true) { P(mutex); critical section; V(mutex); noncritical section; } }

Correctness? sem mx = 1; process CS[i = 1 to n] { while (true) { P(mx); critical section; V(mx); noncritical section; } } Is {I} preserved by P(mx)?

Correctness

What I Teach (Do what I say, not what I do)