Selected Publications 2017/2018 [LICS18] Romain Demangeon, NY: Casual - PowerPoint PPT Presentation

Selected Publications 2017/2018 [LICS’18] Romain Demangeon, NY: Casual Computational Complexity of Distributed Processes. [CC’18] Rumyana Neykova , Raymond Hu, NY, Fahd Abdeljallal: Session Type Providers: Compile-time API Generation for Distributed Protocols with Interaction Refinements in F#. [FoSSaCS’18] Bernardo Toninho, NY: Depending On Session Typed Process. [ESOP’18] Bernardo Toninho, NY: On Polymorphic Sessions And Functions: A Talk of Two (Fully Abstract) Encodings. [ESOP’18] Malte Viering, Tzu-Chun Chen, Patrick Eugster, Raymond Hu , Lukasz Ziarek: A Typing Discipline for Statically Verified Crash Failure Handling in Distributed Systems. [ICSE’18] Julien Lange, Nicholas Ng, Bernardo Toninho, NY : A Static Verification Framework for Message Passing in Go using Behavioural Types [ECOOP’17] Alceste Scala, Raymond Hu, Ornela Darda, NY: A Linear Decomposition of Multiparty Sessions for Safe Distributed Programming.. [COORDINATION’17] Keigo Imai, NY, Shoji Yuen: Session-ocaml: a session-based library with polarities and lenses. [FoSSaCS’17] Julien Lange, NY: On the Undecidability of Asynchronous Session Subtyping. [FASE’17] Raymond Hu, NY: Explicit Connection Actions in Multiparty Session Types. [CC’17] Rumyana Neykova, NY: Let It Recover: Multiparty Protocol-Induced Recovery. [POPL’17] Julien Lange, Nicholas Ng, Bernardo Toninho, NY: Fencing off Go: Liveness and Safety for Channel-based Programming.

Selected Publications 2017/2018 [LICS’18] Romain Demangeon, NY: Casual Computational Complexity of Distributed Processes. [CC’18] Rumyana Neykova , Raymond Hu, NY, Fahd Abdeljallal: Session Type Providers: Compile-time API Generation for Distributed Protocols with Interaction Refinements in F#. [FoSSaCS’18] Bernardo Toninho, NY: Depending On Session Typed Process. [ESOP’18] Bernardo Toninho, NY: On Polymorphic Sessions And Functions: A Talk of Two (Fully Abstract) Encodings. [ESOP’18] Malte Viering, Tzu-Chun Chen, Patrick Eugster, Raymond Hu , Lukasz Ziarek: A Typing Discipline for Statically Verified Crash Failure Handling in Distributed Systems. [ICSE’18] Julien Lange, Nicholas Ng, Bernardo Toninho, NY : A Static Verification Framework for Message Passing in Go using Behavioural Types. [ECOOP’17] Alceste Scala, Raymond Hu, Ornela Darda, NY: A Linear Decomposition of Multiparty Sessions for Safe Distributed Programming. [COORDINATION’17] Keigo Imai, NY, Shoji Yuen: Session-ocaml: a session-based library with polarities and lenses. [FoSSaCS’17] Julien Lange, NY: On the Undecidability of Asynchronous Session Subtyping. [FASE’17] Raymond Hu, NY: Explicit Connection Actions in Multiparty Session Types. [CC’17] Rumyana Neykova, NY: Let It Recover: Multiparty Protocol-Induced Recovery. [POPL’17] Julien Lange, Nicholas Ng, Bernardo Toninho, NY: Fencing off Go: Liveness and Safety for Channel-based Programming.

Concurrency in Go Behavioural type inference Model checking behavioural types Termination checking Summary Static verification framework for Go Overview 2 Model checking Behavioural mCRL2 model checker Types Transform Check safety and liveness and verify Type inference 1 3 Termination checking KITTeL termination prover SSA IR Go source code Address type $ program gap 19 /46 Julien Lange, Nicholas Ng, Bernardo Toninho, Nobuko Yoshida mrg.doc.ic.ac.uk A Static Verification Framework for Message Passing in Go using Behavioural Types

Concurrency in Go Behavioural type inference Model checking behavioural types Termination checking Summary Concurrency in Go Goroutines 1 func main() { 2 ch := make(chan string) 3 go send(ch) go keyword + function call 4 print(<-ch) Spawns function as goroutine 5 close(ch) 6 } Runs in parallel to parent 7 8 func send(ch chan string) { 9 ch <- "Hello Kent!" 10 } 20 /46 Julien Lange, Nicholas Ng, Bernardo Toninho, Nobuko Yoshida mrg.doc.ic.ac.uk A Static Verification Framework for Message Passing in Go using Behavioural Types

Concurrency in Go Behavioural type inference Model checking behavioural types Termination checking Summary Concurrency in Go Channels Create new channel 1 func main() { Synchronous by default 2 ch := make(chan string) 3 go send(ch) Receive from channel 4 print(<-ch) Close a channel 5 close(ch) 6 } No more values sent to it 7 Can only close once 8 func send(ch chan string) { 9 ch <- "Hello Kent!" Send to channel 10 } 21 /46 Julien Lange, Nicholas Ng, Bernardo Toninho, Nobuko Yoshida mrg.doc.ic.ac.uk A Static Verification Framework for Message Passing in Go using Behavioural Types

Concurrency in Go Behavioural type inference Model checking behavioural types Termination checking Summary Concurrency in Go Channels 1 func main() { 2 ch := make(chan string) Also select-case : 3 go send(ch) Wait on multiple channel 4 print(<-ch) operations 5 close(ch) 6 } switch-case for 7 communication 8 func send(ch chan string) { 9 ch <- "Hello Kent!" 10 } 21 /46 Julien Lange, Nicholas Ng, Bernardo Toninho, Nobuko Yoshida mrg.doc.ic.ac.uk A Static Verification Framework for Message Passing in Go using Behavioural Types

Concurrency in Go Behavioural type inference Model checking behavioural types Termination checking Summary Concurrency in Go Deadlock detection 1 func main() { 2 Send message thru channel ch := make(chan string) 3 go send(ch) Print message on screen 4 print(<-ch) 5 close(ch) Output: 6 } $ go run hello.go 7 Hello Kent! 8 func send(ch chan string) { $ 9 ch <- "Hello Kent!" 10 } 22 /46 Julien Lange, Nicholas Ng, Bernardo Toninho, Nobuko Yoshida mrg.doc.ic.ac.uk A Static Verification Framework for Message Passing in Go using Behavioural Types

Concurrency in Go Behavioural type inference Model checking behavioural types Termination checking Summary Concurrency in Go Deadlock detection Missing ’go’ keyword Only one (main) goroutine 1 // import _ "net" 2 func main() { Send without receive - blocks 3 ch := make(chan string) 4 send(ch) // Oops Output: 5 print(<-ch) $ go run deadlock.go 6 close(ch) fatal error: all goroutines 7 } are asleep - deadlock! 8 $ 9 func send(ch chan string) { 10 ch <- "Hello Kent!" 11 } 23 /46 Julien Lange, Nicholas Ng, Bernardo Toninho, Nobuko Yoshida mrg.doc.ic.ac.uk A Static Verification Framework for Message Passing in Go using Behavioural Types

Concurrency in Go Behavioural type inference Model checking behavioural types Termination checking Summary Concurrency in Go Deadlock detection Missing ’go’ keyword 1 // import _ "net" Go’s runtime deadlock detector 2 func main() { Checks if all goroutines are 3 ch := make(chan string) 4 send(ch) // Oops blocked (‘global’ deadlock) 5 print(<-ch) Print message then crash 6 close(ch) 7 Some packages disable it } 8 (e.g. net ) 9 func send(ch chan string) { 10 ch <- "Hello Kent!" 11 } 23 /46 Julien Lange, Nicholas Ng, Bernardo Toninho, Nobuko Yoshida mrg.doc.ic.ac.uk A Static Verification Framework for Message Passing in Go using Behavioural Types

Concurrency in Go Behavioural type inference Model checking behavioural types Termination checking Summary Concurrency in Go Deadlock detection Missing ’go’ keyword 1 import _ "net" // unused 2 func main() { 3 ch := make(chan string) 4 send(ch) // Oops Import unused, unrelated package 5 print(<-ch) 6 close(ch) 7 } 8 9 func send(ch chan string) { 10 ch <- "Hello Kent" 11 } 23 /46 Julien Lange, Nicholas Ng, Bernardo Toninho, Nobuko Yoshida mrg.doc.ic.ac.uk A Static Verification Framework for Message Passing in Go using Behavioural Types

Concurrency in Go Behavioural type inference Model checking behavioural types Termination checking Summary Concurrency in Go Deadlock detection Missing ’go’ keyword 1 import _ "net" // unused Only one (main) goroutine 2 func main() { Send without receive - blocks 3 ch := make(chan string) 4 send(ch) // Oops Output: 5 print(<-ch) 6 close(ch) $ go run deadlock2.go 7 } 8 Hangs: Deadlock NOT detected 9 func send(ch chan string) { 10 ch <- "Hello Kent" 11 } 23 /46 Julien Lange, Nicholas Ng, Bernardo Toninho, Nobuko Yoshida mrg.doc.ic.ac.uk A Static Verification Framework for Message Passing in Go using Behavioural Types

Concurrency in Go Behavioural type inference Model checking behavioural types Termination checking Summary Our goal Check liveness/safety properties in addition to global deadlocks Apply process calculi techniques to Go Use model checking to statically analyse Go programs 24 /46 Julien Lange, Nicholas Ng, Bernardo Toninho, Nobuko Yoshida mrg.doc.ic.ac.uk A Static Verification Framework for Message Passing in Go using Behavioural Types