locust

# Locust

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Locust is an open source performance/load testing tool for HTTP and other protocols. Its developer-friendly approach lets you define your tests in regular Python code.

Locust tests can be run from command line or using its web-based UI. Throughput, response times and errors can be viewed in real time and/or exported for later analysis.

You can import regular Python libraries into your tests, and with Locust's pluggable architecture it is infinitely expandable. Unlike when using most other tools, your test design will never be limited by a GUI or domain-specific language.

To get started right away, head over to the [documentation](http://docs.locust.io/en/stable/installation.html).

## Features

#### Write user test scenarios in plain old Python

If you want your users to loop, perform some conditional behaviour or do some calculations, you just use the regular programming constructs provided by Python. Locust runs every user inside its own greenlet (a lightweight process/coroutine). This enables you to write your tests like normal (blocking) Python code instead of having to use callbacks or some other mechanism. Because your scenarios are “just python” you can use your regular IDE, and version control your tests as regular code (as opposed to some other tools that use XML or binary formats)

```python
from locust import HttpUser, task, between


class QuickstartUser(HttpUser):
    wait_time = between(1, 2)

    def on_start(self):
        self.client.post("/login", json={"username": "foo", "password": "bar"})

    @task
    def hello_world(self):
        self.client.get("/hello")
        self.client.get("/world")

    @task(3)
    def view_item(self):
        for item_id in range(10):
            self.client.get(f"/item?id={item_id}", name="/item")
```

#### Distributed & Scalable - supports hundreds of thousands of users

Locust makes it easy to run load tests distributed over multiple machines. It is event-based (using [gevent](http://www.gevent.org/)), which makes it possible for a single process to handle many thousands concurrent users. While there may be other tools that are capable of doing more requests per