Yaniv Eytani and Timo Latvala University of Illinois at Urbana-Champaign Haifa Verification Conference 2006 Outline ! Concurrent methodologies and tools? " " # !! $ Noise making? % ! & ! $ ! ' ( ) * ) ! A simple example ( )+, - . )001 )001 2 )+- 5 )+. )+/ / )001 3)4 -1 A simple example (Continued) )+, 2 6 )+, 6 )00 )+- 6 )+- - 2 . 2 )+)00 6 )+. )+. )+. 6 )00 6 )+/ )+/ / A Simple example (Continued) - )+, / )+, 6 7 . )+, 8 )+, )+- )00 )+- )+- 6 )00 6 )+. )+- )+)00 )+. Known bugs patterns are usually small 9 % ! & 7 : " ! ) 68 ! ! ! Some observations 3 4 ( & !! ! !! ; % 2 ! ; 3 4 Where is the bug ? - I <- <. <- <. =- =. =- =. - . - . - . - . >- >. >- >. %- %. %- %. " " Where is the bug ? - I <- <. <- <. =- =. =- =. - . - . - . - . >- >. >- >. %- %. %- %. " " Where is the bug? - II ! <=-8 > -9 (! 7) ?+, 8 / 8 % -9 +-:) <. =. . . . 8 > . 9 )+, %. @ " #$ % & ' (' ) Interactions within the program ( <=-8 > -9 / 8 % -9 <. =. . . 78 7 8 .8 >.9 A8 %.9 @ 7 8 78 ) * @ #$ + @ #$ & , @ @ - Removing unrelated switches • <=- <. =. . . . @ * / @ @ 1 0$ 2 ' -8 > -9 (! 7) ?+, 8 / 8 % -9 +-:) . 8 > . 9 )+, %. 2 @ ( @ ) 0 Minimizing Scheduling noise B 9 ' ! 0 ! >) % ! B ! ! 3 ; 4 ! Motivating model < ! 9 3 4 1 C 2 ! C ! 2 C ! A simple approach $ 3' 4 ! 9 ! > 3 9 D B !9 ! 4 3 4 Simple Black box algorithm -6 D ! # 3 4 ! -6 # -$ 2 @ ! ! 9 ! C C = ! ! ; . Tomcat Apachie Logger 78 E 666 ! 7? 6 +7 788 E 8 6 781 F E + 781 F 666 F < ' ! 0 Crawler I 2 -9 !7 ?+ 6 2 .9 + 8 % 7 81 Crawler II B ! ! 78 ) ! >) % ! > ) 786 Additional code used & ) # :B ! ! ( 9 Explaining the bug 3 4 < ! ) < # D 7 8 ! ! Current limitations and future work % B D 3 2 4 ! ) > 6 6$ ? ) ! Acknowledgments > % D G # H % = "< Q&A? Thank You ! The Interleaving Space - Terminology < < ! < 2 ! “Bad” noise can mask the bug ' 2 )+, 6 # 6 ' 2 I +, I 00 )+, 6 6 6 6 6 6 ' - B B G +- )+- )+# 6 I +I 00 B 3 5 )+. .