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Introduction
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What is Tsung?
===============

Tsung (formerly IDX-Tsunami) is a distributed load testing
tool. It is protocol-independent and can currently be used to stress
HTTP, WebDAV, SOAP, PostgreSQL, MySQL, AMQP, MQTT, LDAP and Jabber/XMPP servers.

It is distributed under the GNU General Public License version 2.


What is Erlang and why is it important for Tsung?
==================================================

Tsung's main strength is its ability to simulate a huge number of
simultaneous user from a single machine; moreover, you can distribute
the users on cluster for machines. When used on cluster, you can
generate a really impressive load on a server with a modest cluster,
easy to set-up and to maintain. You can also use Tsung on a cloud like
EC2.

Tsung is developed in Erlang and this is where the power of
Tsung resides.


Erlang is a *concurrency-oriented* programming language.
Tsung is based on the Erlang OTP (Open Telecom Platform) and
inherits several characteristics from Erlang:


Performance
  Erlang has been made to support hundred thousands of
  lightweight processes in a single virtual machine.

Scalability
  Erlang runtime environment is naturally distributed,
  promoting the idea of process's location transparency.

Fault-tolerance
  Erlang has been built to develop robust,
  fault-tolerant systems. As such, wrong answer sent from the server
  to Tsung does not make the whole running benchmark crash.


More information on Erlang on http://www.erlang.org.


Tsung background
================

History:

* Tsung development was started by Nicolas Niclausse in
  2001 as a distributed jabber load stress tool for internal use at
  http://IDEALX.com/ (now OpenTrust).  It has evolved as an open-source
  multi-protocol load testing tool several months later. The HTTP
  support was added in 2003, and this tool has been used for several
  industrial projects.  It is now hosted on github, and
  several companies provide profesionnal support. The list of contributors
  is available in the source archive at https://github.com/processone/tsung/blob/master/CONTRIBUTORS.

* It is an industrial strength implementation of a *stochastic model*
  for real users simulation. User events distribution is based on a Poisson Process. More information on this topic in:

  Z. Liu, N. Niclausse, and C. Jalpa-Villanueva.  **Traffic Model
  and Performance Evaluation of Web Servers**. *Performance Evaluation, Volume 46, Issue 2-3, October 2001*.

* This model has already been tested in the INRIA *WAGON*
  research prototype (Web trAffic GeneratOr and beNchmark). WAGON was
  used in the http://www.vthd.org/ project (Very High Broadband
  IP/WDM test platform for new generation Internet applications, 2000-2004).


Tsung has been used for very high load tests:

* *Jabber/XMPP* protocol:

  * 90,000 simultaneous Jabber users on a 4-node Tsung cluster (3xSun V240 + 1 Sun V440).
  * 10,000 simultaneous users. Tsung was running on a 3-computers cluster (CPU 800MHz).
  * 2,000,000 concurrent users on a single m4.10xlarge instance on EC2 to tests ejabberd scalability

* *HTTP and HTTPS* protocol:

  * 12,000 simultaneous users. Tsung were running on a 4-computers cluster (in 2003).
    The tested platform reached 3,000 https requests per second.
  * 10 million simultaneous users running on a 75-computers cluster, generating more
    than one million requests per second.


Tsung has been used at:


* *DGI* (Direction Générale des impôts): French finance ministry

* *Cap Gemini Ernst & Young*

* *IFP* (Institut Français du Pétrole): French Research Organization
  for Petroleum

* *LibertySurf*

* *Sun* (TM) for their Moodlerooms platform on Niagara processors: https://blogs.oracle.com/kevinr/resource/Moodle-Sun-RA.pdf

* and many other companies
