1. Introduction
***************


1.1. 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.


1.2. 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.


1.3. 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
