Simulation

We now show how the same implementation of a distributed system, which is designated for production deployment, is also executable in simulation mode for stepped debugging, protocol correctness testing, or for repeatable studies of the dynamic behaviour of large-scale peer-to-peer systems.

In order to allow the debugging of code, we require deterministic execution during simulation. We achieve this by executing all events and messages in a deterministic fashion and also removing other sources of randomness.

Possible sources of randomness include:

1. system time
2. random generators
3. thread creation/execution
4. network e.g. latency, packet loss
5. input/output sources

A simulation experiment is specified as a SimulationScenario class that describes the occurence of events such as starting/stopping a node, changing the parameters of the network, or terminating the simulation. Such a SimulationScenario is then executed by the P2pSimulator in a single-threaded, deterministic fashion.

• Introduction to Simulation
  • PingPong Simulation
  • Configuration
  • Global View
• Sources of Randomness
  • System time
  • Random Generators
  • Thread creation
  • Network
  • Input/Output sources
  • Instrumentation Exceptions
• Simulation Scenarios Reference
  • Simulation Events
  • Distributions
  • Operations
  • StochasticProcesses