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 srikanthsastry [at] gmail [dot] com
 Office: 419B, H.R.B.B., TAMU
 Ph: +1 979.862.4535
 Fax: +1 979.847.8578

 

Paper on Crash Quiescence at DISC 2009
Friday, 24 July 2009 14:30

The paper titled "Crash-Quiescent Failure Detection" has been accepted at the 23rd International Symposium on Distributed Computing (DISC 2009).

Here is the abstract:

A distributed algorithm is crash quiescent if it eventually stops sending messages to crashed processes. An algorithm can be made crash quiescent by providing it with either a crash notification service or a reliable communication service. Both services can be implemented in practical environments with failure detectors. Therefore, crash-quiescent failure detection is fundamental to system-wide crash quiescence. We establish necessary and sufficient conditions for crash-quiescent failure detection in partially synchronous environments where a bounded, but unknown, number of consecutive messages can be arbitrarily late or lost. Without a correct majority of processes, not even the weakest oracle for fault-tolerant consensus, <>W, can be implemented crash quiescently. With a correct majority, however, the eventually perfect failure detector,
<>P, is possible. Our <>P algorithm is correct in all runs, but improves performance via crash quiescence in any run with a correct majority. We also present a refinement of our <>P algorithm to mitigate the overhead
of achieving crash quiescence; the resulting bit complexity per utilized link is asymptotically better than or equal to that of non-crash-quiescent counterparts.


Click here for the complete paper.

 
New paper at SPAA 2009
Friday, 29 May 2009 07:16

Our paper titled "The Weakest Failure Detector for Wait-Free Dining under Eventual Weak Exclusion" has been accepted at SPAA 2009 (Symposium on Parallelism in Algorithms and Architectures).

Here is the abstract:

Dining philosophers is a classic scheduling problem for local mutual exclusion on arbitrary conflict graphs. We establish necessary conditions to solve wait-free dining under eventual weak exclusion in message-passing systems with crash faults. Wait-free dining ensures that every correct hungry process eventually eats. Eventual weak exclusion permits finitely many scheduling mistakes, but eventually no live neighbors eat simultaneously; this exclusion criterion models scenarios where scheduling mistakes are recoverable or only affect performance. Previous work showed that the eventually perfect failure detector (<>P) is sufficient to solve wait-free dining under eventual weak exclusion; we prove that <>P is also necessary, and thus <>P is the weakest oracle to solve this problem. Our reduction shows that any such dining solution can be made eventually fair. We also sketch a reduction for proving that the trusting and strong detectors (T + S) are necessary for wait-free dining under the stricter criterion of perpetual weak exclusion, thus resolving an open question posed by Delporte-Gallet et al. in 2005.

 

The paper is available here.

 
New paper at IPDPS 2009
Tuesday, 17 February 2009 17:28

My (well, our) paper titled "Detecting Crash Faults in Celerating Environments" has been accepted in the 23rd IEEE International Parallel and Distributed Processing Symposium (IPDPS). The paper was judged as a best paper in of the conference as well!

Here is the abstract:

 

Failure detectors are a service that provides (approximate) information about process crashes in a distributed system.  The well-known "eventually perfect" failure detector, <>P, has been implemented in partially synchronous systems with unknown upper bounds on message delay and relative process speeds.  However, previous implementations have overlooked an important subtlety with respect to measuring the passage of time in "celerating" environments, in which absolute process speeds can continually increase or decrease while maintaining bounds on relative process speeds.  Existing implementations either use action clocks, which fail in accelerating environments, or use real-time clocks, which fail in decelerating environments.  We propose the use of bichronal clocks, which are a composition of action clocks and real-time clocks.  Our solution can be readily adopted to make existing implementations of <>P robust to process celeration, which can result from hardware upgrades, server overloads, denial-of-service attacks, and other system volatilities.

 Click here for the complete paper.

 
Poster Presentation
Wednesday, 17 September 2008 06:05

The Industry Affiliants Program (IAP) of the Computer Science Dept in Texas A&M had their annual banquet yesterday (Sept 16 2008). Part of it was a poster competition. Here is my entry into the contest:

[IAP poster ppt ]

iap fall 08 085.jpgAnd yeah, I won first place too :)

 

 
Treasure Island
Friday, 05 September 2008 18:53

StageCenter presents R.L.Stevenson's Adventures of Treasure Island starting from Sept 10th 2008. I am playing Ben Gunn. Here is the promo:

StageCenter is a community theater in downtown Bryan. Visit their website http://www.stagecenter.net for details.

 
Proposing a new radio show
Wednesday, 27 August 2008 09:58

I am proposing a new music show on KEOS 89.1FM Community Radio. Below is the proposal I will be submitting to the KEOS mangement team.


  KEOS Show Proposal

Name: Srikanth Sastry
Date:
August 27, 2008
Show Description:
I propose a music show focusing exclusively on Trance music. The show will showcase various sub genres of trance including Progressive Trance, Acid Trance, Psychedelic Trance, Vocal Trance, Ambient Trance, and such. The show will feature artists like ATB, Paul Oakenfold, Paul Van Dyke, Tiesto, Robert Miles, Astral Projection, Buddha Bar, and such. The nature of trance music and the associated culture is such that it favors long sessions of continuous music, so the show will have very few breaks. All the mandated PSAs, promos, and station ID will either be played together so as to provide a longer continuous music session, or will be played over the music (the music will be potted down, of course). Since this makes it difficult to communicate the play-list to the listeners I propose serve the play-list online.

Read more... [Proposing a new radio show]
 
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