package dscheck

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Traced Atomics


Dune Dependency





dscheck — tool for testing concurrent OCaml programs

Experimental model checker for testing concurrent algorithms based on Dynamic Partial-Order Reduction for Model Checking Software. At the core, dscheck runs each test numerous times, exhaustively trying every single interleaving of atomic operations. User-provided assertions are run at the end of every execution.


Dscheck can be installed from opam: opam install dscheck. Sample usage on a naive counter is shown below.

module Atomic = Dscheck.TracedAtomic
(* tested implementation needs to use dscheck's atomic module *)

let test_counter () =
  let counter = Atomic.make 0 in
  let incr () = Atomic.set counter (Atomic.get counter + 1) in 
  Atomic.spawn incr;
  Atomic.spawn incr; (fun () -> Atomic.check (fun () -> Atomic.get counter == 2))

This is a classic example of a race condition with two threads trying to increment a counter without synchronisation. When the race occurs, one of the updates is lost. dscheck finds the interleaving that leads to that:

Found assertion violation at run 12:
Process 0: start 
Process 0: get 1
Process 1: start 
Process 1: get 1
Process 0: set 1
Process 1: set 1
Fatal error: exception File "src/", line 266, characters 6-12: Assertion failed


Contributions are appreciated! Please create issues/PRs to this repo.