ANN: Release 1.9.1 of SimPy (Simulation in Python) package

kgmuller kgmuller at
Mon Mar 17 18:12:55 CET 2008

We announce the availability of SimPy version 1.9.1. This is an important
bug-fix release of SimPy 1.9 which any user of SimPy 1.9 should download.

SimPy 1.9.1 can be downloaded from .

The SimPy homepage is at http://SimPy.SourceForge.Net .

What is SimPy?
SimPy (= Simulation in Python) is an object-oriented, process-based
discrete-event simulation language completely implemented in Python. It is
released under the GNU Lesser GPL (LGPL). SimPy provides the modeler with
components of a simulation model including processes, for active components
like customers, messages, and vehicles, and resources, for passive
components that form limited capacity congestion points like servers,
checkout counters, and tunnels. It also provides monitor variables to aid in
gathering statistics. Random variates are provided by the standard Python
random module.

Many users claim that SimPy is one of the cleanest, easiest to use discrete
event simulation packages! SimPy is in use at many universities, research
institutes and in industry.

SimPy comes with data collection capabilities, GUI and plotting packages. It
can be easily interfaced to other packages, such as plotting, statistics, or
database systems.

SimPy is platform-independent and runs on all systems on which Python 2.3 or
later is available.


The bugs were identified and reported by members of the SimPy user
community. Thanks for this! Collaboration works!

Release notes for SimPy 1.9.1
SimPy 1.9.1 cures two bugs:

(1) Excessive memory requirements of large or long-running scripts. This
performance problem was caused by circular references between Process and
event notice instances.

(2) Runtime errors for pre-empts of processes holding multiple Resource


In addition to all the other, extensive documentation, SimPy 1.9.1 provides
a short manual which only addresses the basic facilities of SimPy. You could
consider this as "SimPy light". This manual is aimed at introducing SimPy to

(end of Release Notes)


Klaus Müller Tony Vignaux

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