Load testing in Rest API - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this simple load test script?

Consider this Python script using the requests library to simulate 3 sequential API calls. What will be printed?

Rest API

import requests

urls = ['https://api.example.com/data1', 'https://api.example.com/data2', 'https://api.example.com/data3']

for url in urls:
    response = requests.get(url)
    print(response.status_code)

A

200
200
200

B

200
404
200

C

404
404
404

D

200
200
404

💡 Hint

Assume all URLs are valid and the server is up.

The script sends GET requests to three valid endpoints. Since the server is up and URLs are correct, each request returns HTTP status 200.

🧠 Conceptual

intermediate

Which factor is most important when designing a load test?

When creating a load test for a REST API, which factor should you prioritize to simulate real user behavior?

A The programming language used to write the test

B Only the total number of requests sent

C The size of the API response payload

D Number of concurrent users and request rate

💡 Hint

Think about what affects server load the most.

The number of concurrent users and how fast requests are sent directly impact server load and performance under stress.

🔧 Debug

advanced

Why does this load test script fail with a connection error?

This Python script uses threading to send 100 requests concurrently but raises a ConnectionError. What is the likely cause?

Rest API

import threading
import requests

def send_request():
    requests.get('https://api.example.com/data')

threads = []
for _ in range(100):
    t = threading.Thread(target=send_request)
    threads.append(t)
    t.start()

for t in threads:
    t.join()

A The URL is invalid causing connection failure

B The requests library does not support threading

C The server limits the number of simultaneous connections causing errors

D Threads are not started properly

💡 Hint

Consider server-side limits on connections.

Many servers limit concurrent connections from a single client. Sending 100 requests at once may exceed this limit, causing connection errors.

📝 Syntax

advanced

Identify the syntax error in this load test script snippet

What is wrong with this Python code snippet for sending multiple requests?

Rest API

import requests

responses = [requests.get('https://api.example.com/data') for i in range(5)]
print(responses.status_code)

A 'responses' is a list; accessing 'status_code' directly causes AttributeError

B Missing parentheses in the print statement

C The range function is used incorrectly

D The requests.get call is missing required headers

💡 Hint

Think about the type of 'responses' and how to access elements.

'responses' is a list of response objects. You cannot call 'status_code' on the list itself; you must access an individual response first.

🚀 Application

expert

How many requests per second does this load test generate?

This script uses asyncio to send 50 requests with a 0.1 second delay between each start. How many requests per second does it generate approximately?

Rest API

import asyncio
import aiohttp

async def fetch(session, url):
    async with session.get(url) as response:
        return await response.text()

async def main():
    async with aiohttp.ClientSession() as session:
        tasks = []
        for _ in range(50):
            tasks.append(fetch(session, 'https://api.example.com/data'))
            await asyncio.sleep(0.1)
        await asyncio.gather(*tasks)

asyncio.run(main())

A 50 requests per second

B 10 requests per second

C 5 requests per second

D 100 requests per second

💡 Hint

Calculate how many requests start each second based on the delay.

Each request starts after 0.1 seconds, so 1/0.1 = 10 requests start per second approximately.