Reliability & rate limiting
Retries, exponential backoff, circuit breakers, token buckets, and idempotent handlers.
How to Implement an Adaptive Rate Limiter in Python
Build an adaptive rate limiter that adjusts request intervals dynamically based on recent error rates, slowing down when failures spike.
import time
import random
class AdaptiveRateLimiter:
"""Simple adaptive rate limiter that reduces requests when error rate is high."""
def __init__(self, min_interval=0.1, max_interval=2.0, error_threshold=0.3):
self.min_interval = min_interval
self.max_interval = max_interval
sel…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):
…How to Mock a Try Confirm Cancel Pattern in Python
Define a simple class with confirm and cancel methods, execute a try confirm with error handling, and print the final state.
class TCC:
def __init__(self):
self.confirmed = False
self.cancelled = False
def confirm(self):
self.confirmed = True
return "confirmed"
def cancel(self):
self.cancelled = True
return "cancelled"
def try_confirm(self):
try:
result =…How to mock a fallback return value in Python
Test a function that returns a default value on failure by mocking requests.get and its side effects.
from unittest.mock import Mock, patch
import requests
def fetch_data(url, default=None):
try:
response = requests.get(url)
response.raise_for_status()
return response.json()
except (requests.RequestException, ValueError):
return default
with patch("requests.get") as mock_get:
…Implement a Circuit Breaker Pattern in Python
This code implements a simple circuit breaker that opens after a threshold of consecutive failures, causing subsequent calls to fail fast without invoking the underlying function.
class CircuitBreaker:
def __init__(self, failure_threshold=3):
self.failure_threshold = failure_threshold
self.failure_count = 0
self.open = False
def call(self, func, *args, **kwargs):
if self.open:
raise RuntimeError("Circuit is open - failing fast")
try:
…Retry with Exponential Backoff and Jitter in Python
A decorator-style retry wrapper that retries a flaky function with exponential backoff plus random jitter, then raises after the last attempt fails.
import random
import time
def retry_with_backoff(func, max_retries=3, base_delay=0.5, max_jitter=0.1):
for attempt in range(max_retries + 1):
try:
return func()
except Exception as e:
if attempt == max_retries:
raise
delay = base_delay * (2 ** at…Browse by section
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Reliability & rate limiting — Python code examples
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