Reference library

Python Code Samples

Medium snippets you can copy, study, and run in the browser editor.

4 matches
Concurrency & performance medium

Limit Concurrency with asyncio.Semaphore in Python

Use asyncio.Semaphore to cap how many async tasks run at once, throttling a batch of coroutines to a set concurrency limit.

asyncio concurrency semaphore
Python 
import asyncio
import random


async def fetch_data(i: int, semaphore: asyncio.Semaphore) -> str:
    async with semaphore:
        print(f"Task {i} starts")
        await asyncio.sleep(random.uniform(0.1, 0.5))
        print(f"Task {i} finishes")
        return f"Result {i}"


async def main() -> None:
    semaphore …
13 0 Open
System design patterns medium

How to Limit Concurrent Requests with a Semaphore in Python

Use threading.Semaphore with a ThreadPoolExecutor to cap how many worker threads run simultaneously, preventing resource overload.

concurrency semaphore threading
Python 
import threading
import time
from concurrent.futures import ThreadPoolExecutor

def worker(name, semaphore, results):
    with semaphore:
        results.append(f"start {name}")
        time.sleep(0.5)  # simulate async work
        results.append(f"done {name}")

def main():
    sem = threading.Semaphore(2)  # max 2 …
14 0 Open
Reliability & rate limiting medium

How to Implement a Bulkhead Pattern with Threading in Python

Implement a bulkhead pattern in Python that isolates concurrent tasks with a bounded semaphore, limiting active workers to prevent resource exhaustion.

bulkhead threading semaphore
Python 
import threading
import time
import random


class Bulkhead:
    def __init__(self, workers: int):
        self._semaphore = threading.BoundedSemaphore(workers)
        self._lock = threading.Lock()
        self._active = 0

    def run(self, task):
        with self._semaphore:
            with self._lock:
          …
13 0 Open
Microservices patterns medium

Bulkhead Thread Pool per Service Mock in Python

Simulates a bulkhead pattern with per-service thread pools and semaphore-based rejection to isolate failures between dependent services.

bulkhead threadpool semaphore
Python 
import threading
import time
import random
from concurrent.futures import ThreadPoolExecutor

class ServiceBulkhead:
    def __init__(self, name, max_threads, max_queue):
        self.name = name
        self.executor = ThreadPoolExecutor(max_workers=max_threads)
        self.semaphore = threading.Semaphore(max_thread…
11 0 Open

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PythonSkillset code samples are short, focused examples organised by topic and difficulty. Every snippet is server-rendered HTML — readable by search engines and easy to copy. Open any sample, read the notes, copy the code, then press Try in editor to run it in the browser with Pyodide.

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  2. Open a sample, read How it works, and copy the code block
  3. Run it in the IDE, tweak values, then take a related quiz or tutorial lesson

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Samples are quick reference — one concept per page. For step-by-step teaching, use our Python tutorials. To test yourself, try quizzes or coding challenges. Clean up style with the Python formatter.

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