Light Weight Concurrency in OCaml:
Continuations, Monads, Promises, Events

Abstract: We explore various methods to implement (very) light weight concurrency in OCaml, in both direct and indirect style. We try in particular to examine the relations between all these various schemes. Three simple example applications allow us to examine both the coding styles and the performances. The cost of context switching, thread creation and the memory footprint of a thread are compared. All implementations are much better than system and VM threads, but the “trampoline” scheme seems to be the best both at CPU and memory requirements.

• Contents
• Introduction
• Concurrency Model
  • Basic Operations
  • Communication
• Three Example Applications
  • Kpn
  • Eratosthene Sieve
  • Concurrent Sort
• Direct Style Implementations
  • Capturing Continuations
  • Delimited Continuations
• Indirect Style Implementations
  • Trampolined Style
  • Continuation Monad
  • Promise Monad
  • Event-based Programming
• Performance
• Conclusion and Perspectives
• References
• Applications Source Code
  • Kpn
  • Sieve
  • Sorter
• Complete Source Code of the Implementations
  • System/VM preemptive scheduling
  • Capturing Continuations
  • Delimited Continuations
  • Trampolined Style
  • Continuation Monad
  • Promise Monad
  • Events

This document was translated from L^AT_EX by H^EV^EA.