Performing File Operations in Locust Load‑Testing Scripts

In Locust, file operations can be performed using Python's standard file handling libraries such as os and io , because Locust scripts are essentially Python scripts.

Basic file operation examples

1. Reading file content

Assume you need to read data from a file and send it as part of an HTTP request.

import os
from locust import HttpUser, task, between
class WebsiteUser(HttpUser):
    wait_time = between(1, 5)

    @task
    def upload_file(self):
        file_path = os.path.join(os.getcwd(), "example.txt")  # Get file path in current working directory
        if os.path.exists(file_path):
            with open(file_path, 'r') as file:
                content = file.read()
                print(content)  # Or process file content as needed
        else:
            print(f"File {file_path} does not exist.")

2. Writing to a file

Sometimes you may need to save some information (e.g., response data) to a file for later analysis.

@task
def save_response_data(self):
    response = self.client.get("/some_endpoint")
    if response.status_code == 200:
        with open("response_data.txt", "w") as file:
            file.write(response.text)

3. File upload

If you need to simulate a user uploading a file, you can use Locust's files parameter.

import os
class WebsiteUser(HttpUser):
    wait_time = between(1, 5)

    @task
    def upload_file_to_server(self):
        file_path = os.path.join(os.getcwd(), "example.txt")  # Assume file is in current working directory
        if os.path.exists(file_path):
            files = {"file": ("example.txt", open(file_path, "rb"))}
            self.client.post("/upload", files=files)
        else:
            print(f"File {file_path} does not exist.")

Note that the example first checks if the file exists, opens it in binary mode for upload, and recommends using a context manager (the with statement) to ensure proper file closure.

Precautions

Exception handling: Add appropriate exception handling for file operations to prevent crashes.

try:
    with open("non_existent_file.txt", "r") as f:
        data = f.read()
except FileNotFoundError as e:
    print(f"Error: {e}")

Concurrency issues: When multiple virtual users read/write the same file, consider lock mechanisms or design tests to avoid such conflicts.

Cleanup: Remove temporary files generated during testing to avoid excessive storage usage.

By following these methods, you can flexibly perform various file operations in Locust scripts to better simulate real user behavior and handle data during testing.