Load Testing with Locust.io
I’ve recently done some load testing using Locust.io. The setup was more complicated than other tools and I didn’t feel like it was well documented on their site. Here’s how I got Locust.io running on two different Linux platforms.
Locust.io on RedHal Enterprise Linux (RHEL)
Naturally, these instructions will work on CentOS too.
sudo yum -y install python-setuptools python-devel sudo yum -y install libevent libevent-devel
One requirement of Locust.io is ZeroMQ. I found instructions to install that on their site http://zeromq.org/distro:centos
sudo yum -y -c http://download.opensuse.org/repositories/home:/fengshuo:/zeromq/CentOS_CentOS-6/home:fengshuo:zeromq.repo install zeromq zeromq-devel sudo easy_install locustio sudo easy_install pyzmq
Locust.io on Debian
sudo apt-get update sudo apt-get -y install python-setuptools sudo apt-get -y install python-dev sudo apt-get -y install libevent-dev sudo apt-get -y install libzmq3-dev sudo easy_install locustio sudo easy_install pyzmq
Running Locust.io Test
Here’s a simple python test script for Locust.io. Save this to a file named locust-example.py.
from locust import HttpLocust, TaskSet, task class UserBehavior(TaskSet): @task def index(self): self.client.get("/") class WebsiteUser(HttpLocust): task_set = UserBehavior min_wait = 1000 max_wait = 3000
At this point you should be ready to run a test. You can run this from any user directory.
locust -H http://220.127.116.11 -f locust-example.py --master& locust -f locust-example.py --slave& locust -f locust-example.py --slave& locust -f locust-example.py --slave&
The first line above specifies the host against which all requests will be executed, an IP address 18.104.22.168 in this case. I start these as jobs that run in the background so I can start up some slaves too. In this case I start three. All the output from these will still go to stdout. You can verify that the processes are running using the jobs command.
debian@locust:~$ jobs  Running locust -H http://22.214.171.124 -f locust-testnginx.py --master &  Running locust -f locust-testnginx.py --slave & - Running locust -f locust-testnginx.py --slave & + Running locust -f locust-testnginx.py --slave &
You can now load the Locust.io user interface in a web browser. Just point to the hostname/IP on port 8089.
After starting up, Locust will spin up clients, distributed among the slaves, until it has reached the desired number. After it reaches the full number of clients it automatically resets the stats and keeps running until it is manually stopped.
That’s it. For better utilization of multiple cores, spin up additional slaves. I keep a locust.io image on hand so I can quickly spin it up when I have load testing to do. Since the test scripts are python, I keep them in the same repositories with the applications under test. Follow this link for full documentation for Locust.io.