More Lust for Load
Charly's Column – Tsung
How many users can the database take? When does a CMS throw in the towel? In order to explore performance limits, Charly Kühnast uses the Tsung load generator instead of human users as beta testers.
If I want to test how much load a (perhaps even distributed) system can take, I launch a load generator. Some time ago, I praised Siege [1] in my column, which I still consider to be a good barrage tool. However, most load generators fire unrealistically from all barrels and do not simulate the behavior of a real user. Tsung [2] can do this better.
Tsung evolved in several evolutionary steps from a tool that ran load tests against Jabber/XMPP servers. Under the fear-inspiring name of idx-Tsunami, it was given multiprotocol capabilities. Since 2014, the development of idx-Tsunami has petered out. Tsung has simply taken the basis and continued developing Tsunami's codebase.
XMPP is still one of the services that Tsung can deploy to cause unrest on its test servers. On top of this, Tsung supports HTTP with and without TLS, WebDAV, SOAP, PostgreSQL, MySQL, AMQP, MQTT, and LDAP. All protocols are integrated via a plugin engine, so further protocols can follow at any time.
Planning the Attack Using XML
Using XML configuration files, the Tsung user designs their load test scenarios in detail. For example, you can stipulate that the requests should not only originate from one machine, but that several load generators (or clients) should play a key role. I can assign more or less work to clients with different performance characteristics by using weighting. I can also configure several back-end servers. IPv4 and IPv6 are allowed for the connections, also in mixed mode.
The details of the requests that Tsung uses to stress the servers can be configured within a wide range. In order to simulate realistic user behavior, the software does not torment the servers with constant fire on request, but instead makes well-planned pauses, just as a human user would if he or she were looking at the content of a website and then clicking on it.
Reception Center
If you want to make it even more realistic, use the supplied recorder: After starting, it records the behavior of one or more users, and Tsung replicates this session later. For example, variables can be brought into play when simulated users enter data in a search mask.
I can bundle a group of requests into one transaction. Tsung understands this term as a logically related request, for example: A user calls the website, authenticates themselves (say, using OAuth), then accesses the sub-page using the search function, and submits a search query.
Statistics Reveal All to the Administrator
In addition to the existing evaluations of the load behavior for the back-end servers, Tsung also generates reports on the performance of such transactions (Figure 1). These statistics are, as expected, more useful for the behavior of the systems in production than synthetic flak tests – and that's exactly what I like about Tsung.

Infos
Buy this article as PDF
(incl. VAT)
Buy Linux Magazine
Direct Download
Read full article as PDF:
Price $2.95
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Find SysAdmin Jobs
News
-
MNT Seeks Financial Backing for New Seven-Inch Linux Laptop
MNT Pocket Reform is a tiny laptop that is modular, upgradable, recyclable, reusable, and ships with Debian Linux.
-
Ubuntu Flatpak Remix Adds Flatpak Support Preinstalled
If you're looking for a version of Ubuntu that includes Flatpak support out of the box, there's one clear option.
-
Gnome 44 Release Candidate Now Available
The Gnome 44 release candidate has officially arrived and adds a few changes into the mix.
-
Flathub Vying to Become the Standard Linux App Store
If the Flathub team has any say in the matter, their product will become the default tool for installing Linux apps in 2023.
-
Debian 12 to Ship with KDE Plasma 5.27
The Debian development team has shifted to the latest version of KDE for their testing branch.
-
Planet Computers Launches ARM-based Linux Desktop PCs
The firm that originally released a line of mobile keyboards has taken a different direction and has developed a new line of out-of-the-box mini Linux desktop computers.
-
Ubuntu No Longer Shipping with Flatpak
In a move that probably won’t come as a shock to many, Ubuntu and all of its official spins will no longer ship with Flatpak installed.
-
openSUSE Leap 15.5 Beta Now Available
The final version of the Leap 15 series of openSUSE is available for beta testing and offers only new software versions.
-
Linux Kernel 6.2 Released with New Hardware Support
Find out what's new in the most recent release from Linus Torvalds and the Linux kernel team.
-
Kubuntu Focus Team Releases New Mini Desktop
The team behind Kubuntu Focus has released a new NX GEN 2 mini desktop PC powered by Linux.