2. Features

2.1. Tsung main features

  • High Performance: Tsung can simulate a huge number of simultaneous users per physical computer: It can simulates thousands of users on a single CPU (Note: a simulated user is not always active: it can be idle during a thinktime period). Traditional injection tools can hardly go further than a few hundreds (Hint: if all you want to do is requesting a single URL in a loop, use ab; but if you want to build complex scenarios with extended reports, Tsung is for you).
  • Distributed: the load can be distributed on a cluster of client machines
  • Multi-Protocols using a plug-in system: HTTP (both standard web traffic and SOAP), WebDAV, Jabber/XMPP and PostgreSQL are currently supported. LDAP and MySQL plugins were first included in the 1.3.0 release.
  • SSL support
  • Several IP addresses can be used on a single machine using the underlying OS IP Aliasing
  • OS monitoring (CPU, memory and network traffic) using Erlang agents on remote servers or SNMP
  • XML configuration system: complex user’s scenarios are written in XML. Scenarios can be written with a simple browser using the Tsung recorder (HTTP and PostgreSQL only).
  • Dynamic scenarios: You can get dynamic data from the server under load (without writing any code) and re-inject it in subsequent requests. You can also loop, restart or stop a session when a string (or regexp) matches the server response.
  • Mixed behaviours: several sessions can be used to simulate different type of users during the same benchmark. You can define the proportion of the various behaviours in the benchmark scenario.
  • Stochastic processes: in order to generate a realistic traffic, user thinktimes and the arrival rate can be randomized using a probability distribution (currently exponential)

2.12. Complete reports set

Measures and statistics produced by Tsung are extremely feature-full. They are all represented as a graphic. Tsung produces statistics regarding:

  • Performance: response time, connection time, decomposition of the user scenario based on request grouping instruction (called transactions), requests per second
  • Errors: Statistics on page return code to trace errors
  • Target server behaviour: An Erlang agent can gather information from the target server(s). Tsung produces graphs for CPU and memory consumption and network traffic. SNMP and munin is also supported to monitor remote servers.

par Note that Tsung takes care of the synchronization process by itself. Gathered statistics are «synchronized».

It is possible to generate graphs during the benchmark as statistics are gathered in real-time.

2.13. Highlights

Tsung has several advantages over other injection tools:

  • High performance and distributed benchmark: You can use Tsung to simulate tens of thousands of virtual users.
  • Ease of use: The hard work is already done for all supported protocol. No need to write complex scripts. Dynamic scenarios only requires small trivial piece of code.
  • Multi-protocol support: Tsung is for example one of the only tool to benchmark SOAP applications
  • Monitoring of the target server(s) to analyze the behaviour and find bottlenecks. For example, it has been used to analyze cluster symmetry (is the load properly balanced ?) and to determine the best combination of machines on the three cluster tiers (Web engine, EJB engine and database)