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SUMMARY:Birrell's distributed reference listing revisited - Richard Jones\
 , University of Kent
DTSTART:20071107T141500Z
DTEND:20071107T151500Z
UID:TALK8145@talks.cam.ac.uk
CONTACT:Timothy G. Griffin
DESCRIPTION:The Java RMI collector is arguably the most widely used distri
 buted garbage\ncollector. Its distributed reference listing algorithm was 
 introduced by\nBirrell in the context of Network Objects\, where the descr
 iption was informal\nand heavily biased toward implementation. In this pap
 er\, we formalise this\nalgorithm in an implementation-independent manner\
 , which allows us to clarify\nweaknesses of the initial presentation. In p
 articular\, we discover cases\ncritical to the correctness of the algorith
 m that are not accounted for by\nBirrell. We use our formalisation to deri
 ve an invariant-based proof of\ncorrectness of the algorithm that avoids n
 otoriously difficult temporal\nreasoning. Furthermore\, we offer a novel g
 raphical representation of the state\ntransition diagram\, which we use to
  provide intuitive explanations of the\nalgorithm and to investigate its t
 olerance to faults in a systematic manner.\nFinally\, we examine how the a
 lgorithm may be optimised\, either by placing\nconstraints on message chan
 nels or by tightening the coupling between\napplication program and distri
 buted garbage collector.\n\n"http://www.cs.kent.ac.uk/people/staff/rej/gc.
 html":URL
LOCATION:Lecture Theatre 1\, Computer Laboratory
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