How to Write a Scenario

Scenarios describe how you want MZBench to behave during the benchmark. If you’re testing an online store, your scenario will probably include opening a product page and adding the product to cart. For a search service, the scenario may be searching for a random word. You get the idea.

Here’s how you write a scenario to load-test a locally running web app.

  1. Create a file called myscenario.bdl with this content:

    pool(size = 1,
     worker_type = http_worker):
    connect("localhost", 8080)
    get("/")

    Scenarios are written in special language similar to Python in some aspects. Here’s what this scenatio means, step by step:

    pool(size = 1,
     worker_type = http_worker):

    Here we define a pool of workers, namely one worker of type http_worker. Workers of this type can send GET and POST HTTP requests, which is exactly what we need.

        connect("localhost", 8080)
    get("/")

    Here we define the actions that each worker in the pool must perform: connect the target by host and port and send a single GET request to the “/” endpoint, i.e. to http://localhost:8080/.

  2. Launch the MZBench server and start your scenario:

    $ ./bin/mzbench start_server
Executing make -C /path/to//mzbench/bin/../server generate
.........
Waiting for server application start
Webserver is started at http://127.0.0.1:4800
Active config file is ~/.config/mzbench/server.config
ok

$ ./bin/mzbench start /path/to/myscenario.bdl
{
    "status": "pending",
    "id": 107
}

  3. Go to localhost:4800 and see your benchmark run and complete:

    Single Request

    Great, it works! But one request isn’t going to load your web app too much, is it? Let’s extend our scenario to generate some proper load.

  4. Modify myscenario.bdl so that it looks like this:

    pool(size = 1,
     worker_type = http_worker):
        connect("localhost", 8080)
        loop(time = 1 min,
             rate = 10 rps):
                get("/")

    We’ve replaced a single GET request with a loop that sends 10 requests per second for 1 minute.

  5. Start the modified scenario:

    $ ./bin/mzbench start /path/to/myscenario.bdl
{
    "status": "pending",
    "id": 109
}

    Go to localhost:4800 to see a graph updated in real time as your benchmark is running:

    50 RPS