Reference library

Reliability & rate limiting

Retries, exponential backoff, circuit breakers, token buckets, and idempotent handlers.

4 matches

How to Mock Fault Injection Percentage in Python

Simulate a service with a 30% failure rate using random.random to test error handling and retries.

import random

class Service:
    def call(self):
        if random.random() < 0.3:  # 30% failure rate
            raise ConnectionError("Simulated network fault")
        return "ok"

def main():
    svc = Service()
    random.seed(42)  # deterministic for demonstration
    results = []
    for _ in range(10):
     …

14 0 Open

Reliability & rate limiting easy

How to Retry on Specific Exception Tuples in Python

A decorator-based retry pattern that retries a function only when it raises exceptions specified in a tuple, with configurable retries and delay.

retry decorator exceptions

Python

import time
import random
from unittest.mock import patch


def retry_on_exceptions(retries=3, exceptions=(ValueError,), delay=0.1):
    def decorator(func):
        def wrapper(*args, **kwargs):
            for attempt in range(retries):
                try:
                    return func(*args, **kwargs)
          …

15 0 Open

Reliability & rate limiting easy

How to implement an idempotency key store in Python

Build an in-memory idempotency key store with TTL that processes a request once and reuses the cached result for duplicate calls.

idempotency cache ttl

Python

import hashlib
import time
from typing import Dict, Optional


class IdempotencyStore:
    """Simple in-memory idempotency key store with mock processing."""

    def __init__(self, ttl_seconds: int = 3600) -> None:
        self.ttl = ttl_seconds
        self._store: Dict[str, tuple[str, float]] = {}

    def _is_expi…

15 0 Open

Reliability & rate limiting easy

How to implement rate limiting in Python

A beginner-friendly Python rate limiter that throttles API calls and retries parsing tasks with exponential backoff.

rate-limiting retry parsing

Python

import time
import random

class RateLimiter:
    def __init__(self, max_calls, per_seconds):
        self.max_calls = max_calls
        self.per_seconds = per_seconds
        self.timestamps = []
    
    def allow(self):
        now = time.time()
        self.timestamps = [t for t in self.timestamps if now - t < sel…

15 0 Open

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