Simulation Research GroupA Controller for Distributed Discrete-Event Simulation: Akaroa2

Group Leaders:

Krys Pawlikowski1, Don McNickle2, Greg Ewing1

1 Department of Computer Science and Software Engineering 2 Department of Management

Group Members:  

Will Gittoes, Yumi Masuri, Adriaan Schmidt, Mirko Eickhoff

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Distributed Discrete-Event Simulation

Two Different Approaches:

• Break problem up into bits that can (nearly) be done in parallel – e.g. Timewarp

• Difficult to do, high communication costs, modest speed-up

• Speed up simulation by launching multiple replications in parallel – e.g. Akaroa2

• Easy to launch multiple replications, low communication cost, nearly linear speed-up

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Akaroa2

• Launches identical replications of a simulation on a network

• Written in C++, works under most OS

• Only one extra line in the simulation program required

• User specifies the level of accuracy required, then the simulation runs until that is achieved

• Downloaded 1700 times from www.akaroa.canterbury.ac.nz

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Akaroa2 on PlanetLab

Simulating this problem

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Problems that Akaroa2 addresses

Problems Solutions

Speed Even simple systems may

need millions of events

Appropriate Accuracy for Decision-Making

Runs are either wastefully long, or not accurate enough

Multiple replications in parallel

Automated run-length control

Automated statistical analysis of results

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Akaroa2: Architecture

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Akaroa2: Interface

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Akaroa2: Features

• Indifferent to fast or slow processors

• High fault tolerance: A dead processor is no different to a slow one

• Nearly linear speed-up: n processors produce results in 1/n of the time

• Extensively tested simulation features: RNG’s, transient analysis, confidence interval estimation

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Akaroa2: Use on PlanetLab

• Requires very low bandwidth

• After set-up the communication is entirely one way and does not need acknowledgement

• In principle can be distributed over any set of hosts on the Internet – e.g. PlanetLab

No difference in simulation speed

Distributing Akaroa2 on PlanetLab Farzana, Ewing, Pawlikowski, Yamada, 2009

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Extension to Other Data Streams

Much of the expertise built up over the last 20 years with Akaroa2 can be transferred to non-simulation data:

• A reliable, fault-tolerant architecture

• Analysis of streams of data from multiple sources

• Analysis methods for correlated streams of data