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System design patterns

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

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Object Pool Pattern for Database Connections in Python

Implements a reusable connection pool with acquire/release and context manager support, mocking database connections with idle reuse and exhaustion handling.

object-pool connection-pool databases
Python 
import time
from contextlib import contextmanager
from collections import deque


class ConnectionPool:
    def __init__(self, size=3, max_idle=5):
        self._idle = deque(maxlen=max_idle)
        self._active = set()
        self.size = size

    def _create(self):
        return {"created_at": time.time(), "queri…
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