Skip to main content

Load testing with Java: Pound on a resource with multiple threads

Load testing involves multiple threads or processes performing operations against a resource. For example, execute a query against a database server via 50 concurrent threads. The tricky part is waiting for the threads to start up before the commands are actually executed, in order to make sure that the resource is truly getting hammered. Here's an example of how to accomplish this in Java. It is possible to refactor the following code into a utility accepts two parameters: the number of threads and a lambda expression which can be passed as a Runnable object.

final int numThreads = 50;
ExecutorService executor = Executors.newFixedThreadPool(numThreads);
CountDownLatch ready = new CountDownLatch(numThreads);
CountDownLatch start = new CountDownLatch(1);
CountDownLatch done = new CountDownLatch(numThreads);
for (int j = 0 ; j < numThreads ; j++) {
   executor.execute(() -> {
ready.countDown();
try {
   start.await();
// do something here ...
} catch (InterruptedException ex) {
   Thread.currentThread().interrupt();
} finally {
   done.countDown();
}
   });
}
// wait until everybody is ready
ready.await();

// start
start.countDown();
// wait until everybody is done
done.await();

// clean up the thread pool
executor.shutdownNow();
executor.awaitTermination();

Comments

Popular posts from this blog

Running 2560x1080 on LG 29UM57-P on an old MacBook Pro OSX El Capitan

Yes. A mid-2011 MacBook Pro running OSX El Capitan can drive a 2560x1080 monitor via HDMI.
I was not able to get 60 Hz working. I am settling with 53 Hz. I tried many settings before finding something that works. The refresh rate seems fine to me. Maybe the text could be clearer but for a $200 monitor running this resolution, I'll take it. Apple MacBook 2015 retina resolution is 2560 x 1800. Consider buying a better monitor that may literally give you fewer headaches. Install SwitchResXFollow the instructions for disabling SIPAfter rebooting, run SwitchResX via System PreferencesSelect your LG monitorClick Custom ResolutionsClick the + icon Enter these settings (source)Exit SwitchResX and saveRebootRun SwitchResX via System PreferencesSelect your LG monitorClick Current ResolutionsSelect the 2560x1080, 53 Hz settingEnable SIPIf you discover better settings, please leave a comment.

Collecting and graphing metrics via Apache Camel, Statsd, and Graphite

If you're curious about Apache Camel's metrics reporting via Dropwizard, this guide will help you get Graphite running in a Docker container. Then you will run an instrumented Camel application and view its metrics via Graphite's browser UI.

(1) Install Docker

There are many ways to do this depending on your platform. Google it.

(2) Install and run the Docker container for Statsd and Graphite

Refer to https://github.com/hopsoft/docker-graphite-statsd

The instructions infer that you can run the container without specifying port mappings. This is plain wrong. So use the following command to start the container:

docker run -d --name graphite --restart=always -p 80:80 -p 8125:8125/udp hopsoft/graphite-statsd It is not necessary to enable Graphite's UDP listener. Statsd receives metrics via UDP and forwards them to Graphite over TCP. (3) On Windows and OSX, determine the IP address of the graphite Docker container

On Linux, you can use localhost.

On Windows and OSX, there are…

As California Burns

For the past week, San Franciscans have been wearing respirators to protect their lungs from California's burned carcass in the sky.

Some of the particulates were once human flesh and expensive multi-story homes. Some were paint, pesticides, car batteries, and insulation.

One in five people are wearing masks matter-of-factly. No hysterics. No protests. No mention of the motherfuckers who brought catastrophic runaway climatic heating to our state, burning Californians alive without any warning.

What will Kamala Harris and Dianne Feinstein do after the cadaver dogs leave Paradise? They'll do the same as Repiglicans. They'll do what they've done their entire careers. They will say and do nothing to save us. That’s why they’re senators.