molotov

library2.6pypypi✓ verified 85d ago

Molotov is a simple, Python 3.7+ tool for writing load tests. It is built upon `asyncio` and `aiohttp.client`, enabling highly concurrent testing scenarios. The current version is 2.6, released in October 2022. While there isn't a fixed release cadence, updates address Python compatibility, dependency changes, and new features.

testing http-networking

pip install molotov

package ↗homepage ↗

INSTALL

IMPORT

SIG · MOLOTOV

molotov

testingpythonv2.6

Install

5.8s avg

Import

427ms

Disk

40MB

Pass rate

10/ 10

Env Coverage10 / 10

glibc

3.9–3.13

musl

3.9–3.13

Install & Compatibility

Where this runs

tested against v2.6 · pip install

no network on importno background threads

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

py 3.10–3.920 runs

installs and imports cleanly · install 0.0s · import 0.439s · 42.1MB

glibc

py 3.10–3.920 runs

installs and imports cleanly · install 5.8s · import 0.415s · 44MB

40MB installed

● package 40MB

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

scenario

✓ from molotov import scenario

The primary decorator for defining load test scenarios.

setup

✓ from molotov import setup

Decorator for worker-level setup.

global_setup

✓ from molotov import global_setup

Decorator for test-wide setup, executed once before processes and workers.

get_context

✓ from molotov import get_context

Used to access session-specific data within scenarios or fixtures.

This quickstart defines two asynchronous scenarios that make GET requests to a target API. Each scenario receives an `aiohttp.ClientSession` object. The `weight` parameter controls the probability of a scenario being picked. To run, save this as `loadtest.py` and execute from the terminal.

import os from molotov import scenario _API = os.environ.get('MOLOTOV_TARGET_API', 'http://localhost:8080') @scenario(weight=40) async def scenario_one(session): async with session.get(_API) as resp: res = await resp.json() assert res["result"] == "OK" assert resp.status == 200 @scenario(weight=60) async def scenario_two(session): async with session.get(_API) as resp: assert resp.status == 200

molotov --version

Debug

Known issues

breakingMolotov version 2.5 dropped support for Python 3.6. Version 2.0 dropped support for Python 3.5. Ensure you are running Python 3.7 or superior for Molotov 2.6.

fix

Upgrade your Python environment to 3.7+ (e.g., Python 3.10 for optimal compatibility with Molotov 2.5+).

affects: 2.0, 2.5+

breakingIn Molotov 2.6, the internal multiprocessing library switched from `multiprocessing_on_dill` to `multiprocess`. While typically backward compatible, custom extensions or complex setups interacting directly with multiprocessing internals might require adjustments.

fix

Review any custom multiprocessing logic in your test scripts; ensure compatibility with the `multiprocess` library.

affects: 2.6+

deprecatedThe `aiomeasures` dependency was removed in Molotov 2.4 as the project is no longer maintained. Molotov now uses `aiodogstatsd` for statsd integration.

fix

If you were relying on `aiomeasures`, migrate your metrics collection to use `aiodogstatsd` or other supported alternatives.

affects: 2.4+

gotchaMolotov does not officially support Windows systems, especially concerning multiprocessing features. While basic functionality might work, distributed testing is not reliable.

fix

Run Molotov on Linux or macOS environments for reliable load testing, or within a Docker container.

affects: All versions

breakingMolotov 2.2 removed the `--disable-dns-resolver` option, as DNS resolution is now handled by `aiohttp`.

fix

Remove `--disable-dns-resolver` from your Molotov command-line arguments. Configure `aiohttp` directly if specific DNS behavior is required.

affects: 2.2+

Errors

Common errors & fixes

TypeError: scenario() takes 1 positional argument but 2 were given

Scenarios are asynchronous coroutines and must accept a `session` object as their first argument.

fix

Define your scenario functions as `async def my_scenario(session): ...`

ModuleNotFoundError: No module named 'molotov'

Molotov is not installed in the current Python environment.

fix

Run `pip install molotov` to install the library.

molotov.errors.MolotovError: Expected a coroutine

A function decorated with `@scenario` (or other async-expecting decorators) was defined as a regular function (`def`) instead of an asynchronous one (`async def`).

fix

Change the function definition from `def` to `async def`.

certifi.errors.NoCACertificatesError: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: unable to get local issuer certificate

Python's SSL module cannot find the necessary root SSL certificates to verify HTTPS connections, common in some Python installations or virtual environments.

fix

Install `certifi` and ensure your Python environment is configured to use it, or run `pip install certifi` and re-run your tests. In some cases, you might need to run a specific `Install Certificates.command` on macOS.

Upgrade

Version history

2.6latest on PyPI · released Oct 21, 2022

Audit

Dependencies

aiohttprequiredCore HTTP client for asynchronous requests.

multiprocessrequiredUsed for multiprocessing, replaced 'multiprocessing_on_dill' in 2.6.

Agent activity

6 hits · last 30 days

node

Resources

packagehttps://pypi.org/project/molotov/ ↗

homepagehttps://molotov.readthedocs.io ↗