Design a Connection Pool

Problem

Design a thread-safe connection pool (e.g., DB or socket connections).

Requirements

• acquire(timeout) / release(conn)
• Max pool size; block or fail on exhaustion
• Health-check and recycle stale connections

What evaluators look for

• Thread safety and no leaks
• Fairness for waiters
• Clean separation of pool vs connection lifecycle

Extension

Add dynamic resizing under load and connection validation on borrow.