02152 Concurrent Systems        Fall 2008
Thursday, September 11

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Building 308, Auditorium 12

13.00-15.00	Properties of concurrent programs [Some slides (ps)(pdf)] Critical Regions Lock protocols [Some slides (ps)(pdf)]
	Invariants Proof of invariants

Building 308, G-databar, rooms 15+16

15.00-17.00

CP Lab 2: Data Parallel Algorithm in Java

Texts

Today	Critical regions:[Andrews 3.1] + slides (ps)(pdf) Invariants: [Basic 3.1-3.4]
Coming	Invariant proofs: [Basic 3.5] [skip 3.5.2] Spin locks: [Andrews 3.2-3.3] Barriers: [Andrews 3.4]
Exercises	1. Do Share.1 [in Auxiliary Exercises [aux p.3]]

Remark

There is a slight deviation in the definitions of critical references in [Basic] and [Andrews] although they express the same idea. For an assignment statement, x : = e, Andrews in Def. (2.2) at page 52, only considers the critical references within the expression e and then uses cases on x to determine whether the whole statement satisfies the At-most-once-property. Ie., Andrews does not explicitly consider whether the assignment to x is critical or not.

In [Basic] the assignment to x may itself be considered a critical reference (viz. if x is read by other processes). This way the definition is simplified to the rule of at-most-one-critical-reference.

In any case of discrepancy between [Andrews] and [Basic], the notions of [Basic] are used in this course.

Hans Henrik Løvengreen, Sep 11, 2008