Enhancing KiWi - Scalable Concurrent Key-Value Map

We​ ​take​ ​a​ ​relatively​ ​fresh​ ​wait-free,​ ​concurrent​ ​sorted​ ​map​ ​called​ ​KiWi,​ ​fix​ ​and​ ​enhance​ ​it. First,​ ​we​ ​test​ ​its​ ​linearizability​ ​by​ ​fuzzing​ ​and​ ​applying​ ​Wing&Gong​ ​[2]​ ​linearizability​ ​test. After​ ​fixing​ ​a​ ​few​ ​bugs​ ​in​ ​the​ ​algorithm​ ​design​ ​and​ ​its​ ​implementation,​ ​we​ ​enhance​ ​it.​ ​We design,​ ​implement​ ​and​ ​test​ ​two​ ​new​ ​linearizable​ ​operations​ ​sizeLowerBound()​ ​and sizeUpperBound().​ ​We​ ​further​ ​compose​ ​these​ ​operations​ ​to​ ​create​ ​more​ ​useful​ ​operations. Last,​ ​we​ ​evaluate​ ​the​ ​map​ ​performance​ ​because​ ​previous​ ​evaluations​ ​became​ ​obsolete​ ​due to​ ​our​ ​bug​ ​corrections. KiWi​ ​-​ ​OCC​ ​Key-Value​ ​Map 1 Abstract 1 1.​ ​Preface 2 1.2​ ​KiWi​ ​data​ ​structure​ ​overview​ ​-​ ​emphasis​ ​on​ ​intra-chunk​ ​management. 2 1.2.1​ ​Data​ ​structure​ ​organization 2 1.2.2​ ​Data​ ​Structure​ ​Invariants 3 1.2.3​ ​Brief​ ​description​ ​of​ ​basic​ ​operations 3 2.​ ​Our​ ​contribution 4 2.1​ ​Linearizable​ ​size​ ​bounds 4 2.1.1​ ​Size​ ​Lower​ ​Bound​ ​Design 5 2.1.1.1​ ​The​ ​basic​ ​idea 5 2.1.1.2​ ​More​ ​details​ ​and​ ​Pseudocode 5 2.2​ ​Composition​ ​of​ ​linearizable​ ​operations 8 2.2.1​ ​Motivation 8 2.2.2​ ​Composing​ ​lower&upper​ ​bounds​ ​to​ ​get​ ​isEmpty() 9 2.2.3​ ​Composing​ ​lower&upper​ ​bounds​ ​to​ ​get​ ​size() 9 2.3​ ​Performance​ ​evaluations 10 2.3.1​ ​Competing​ ​Data​ ​Structures 10 2.3.2​ ​Tested​ ​Workloads 10 2.3.2​ ​Benchmark​ ​results​ ​discussion 14 2.3.4​ ​Technical​ ​details 14 2.4​ ​Testing​ ​for​ ​linearizability 14 2.4.1​ ​Generating​ ​histories​ ​from​ ​real​ ​executions 15 2.4.2​ ​Generating​ ​useful​ ​executions 15 03/09/2017 Assaf​ ​Yifrach [email protected] Niv​ ​Gabso [email protected]​​ ​​ ​/​ ​[email protected] 2 2.4.2​ ​Testing​ ​a​ ​concurrent​ ​history 15 2.5​ ​Bug​ ​fixes 15 2.5.1​ ​Comparison​ ​by​ ​data​ ​index​ ​and​ ​order​ ​index 15 2.5.2​ ​Make​ ​the​ ​get()​ ​operation​ ​to​ ​always​ ​consider​ ​the​ ​item​ ​from​ ​PPA 15 2.5.3​ ​Insert​ ​null​ ​into​ ​the​ ​linked​ ​list​ ​even​ ​if​ ​the​ ​key​ ​does​ ​not​ ​exist 16 2.5.4​ ​Rewrite​ ​ChunkInt.copyRange()​ ​method 16 4.​ ​Future​ ​Work 16 5.​ ​References 18