New cool stuff on loadimpact.com
Today we performed a site update, with some new functionality and bug fixes. Most of the fixes are behind the scenes stuff that is not immediately visible to users, but we do have one thing that stands out and which can be seen by all registered users and that is our new test validation feature.
Now, when you create a new test configuration, you will see this on the edit test page:
All tests have to be validated before they can be run. What this means is that when a test configuration is created or changed, we force people to "validate" the configuration before they can start a test using it. The reason we do so is because it allows early detection of load script problems, DNS problems, or quota problems that would prevent the test from being run. We have had many instances where users configure a test and start it, only to find that there is some problem with the test that causes it not to run properly. The test validation feature is meant to allow early warning/prevention of these problems. When you validate a test configuration, what happens behind the scenes is that we run a very short, 1-client test using your configuration. If everything goes well, the test is considered to have validated OK, but if there is an error somewhere, you will see an error message that looks something like this:
We think this feature is going to make it a lot less likely that people misconfigure their tests, and don't notice until they try to run them. The validation feature removes all sleep statements from load scripts when they are being validated, in order to make validation faster. This means that all validations should be fairly quick and painless.
But wait, there is more!
New back end load generator
This is a major change behind the scenes. We have replaced the old load generator, myLoad, with our next-generation load generator rLoad. Both are highly efficient programs, written in C and designed to be able to simulate a lot of clients in a very resource-efficient manner. The main difference between the two is that the new load generator has scripting capabilities and a lot of other features we were missing from the old one. The scripting features are turned off at the moment, because we still need to implement some support systems that are necessary for scripting functionality in Load Impact. However, there are some other features we gain access to immediately. For instance, rLoad will use all available IP addresses when generating load traffic. This means that when you run a 50-client load test on e.g. the Stockholm2 load generator, you will now see traffic from 50 different IP addresses hitting your site. The Stockholm1 and Stockholm2 load generators have 125 IP addresses each, so tests up to 125 simulated clients means the clients will all have unique, individual IPs. If you run larger tests than that, the 125 adresses will be used by the clients in a round-robin fashion. Here is an FAQ entry listing the IP addresses used by all our load generator nodes: http://loadimpact.com/forum/viewtopic.php?id=133
The informed reader will note that Stockholm2 is a new load generator node, and that Stockholm1 has also changed its IP range from before. We recently upgraded the Stockholm nodes and gave them their own class C network where they have plenty of IP addresses to use for load generation. This might mean, however, that some Load Impact users need to upgrade their firewall settings to allow traffic from the new IPs.
