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System design patterns

Sharding, load balancing, CAP tradeoffs, and scaling patterns — interview and production ready.

3 matches

Circuit Breaker Pattern in Python: Closed, Open, and Half-Open States

Implement a circuit breaker with closed, open, and half-open states to prevent repeated calls to failing services and allow recovery after a timeout.

circuit-breaker resilience fault-tolerance

Python

class CircuitBreaker:
    def __init__(self, failure_threshold=3, timeout_seconds=5):
        self.failure_threshold = failure_threshold
        self.timeout_seconds = timeout_seconds
        self.state = "closed"
        self.failure_count = 0
        self.last_failure_time = None

    def record_success(self):
     …

16 0 Open

System design patterns medium

How to Implement the Flyweight Pattern in Python

Implements the Flyweight design pattern to share immutable intrinsic state (character + font) across many document objects, reducing memory usage.

flyweight design-patterns memory-optimization

Python

class Character:
    """Flyweight - stores only intrinsic state (shared)."""

    def __init__(self, char: str, font: str):
        self.char = char
        self.font = font

    def render(self, size: int) -> str:
        return f"{self.char}_{self.font}_{size}"


class CharacterFactory:
    """Flyweight factory - ma…

15 0 Open

System design patterns medium

Singleton Config Loader in Python with Caution

Implements a singleton config loader in Python that reads JSON config files, but demonstrates the hidden gotcha of shared state across instances.

singleton config design-patterns

Python

import json
from pathlib import Path

class ConfigLoader:
    _instance = None

    def __new__(cls, *args, **kwargs):
        if cls._instance is None:
            cls._instance = super().__new__(cls)
        return cls._instance

    def __init__(self, config_file="config.json"):
        if not hasattr(self, "loaded…

12 0 Open

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