How does `ConcurrentHashMap` handle thread safety?

ConcurrentHashMap ensures thread safety by dividing the map into segments and allowing multiple threads to access different segments concurrently. It locks only the segment being modified, not the entire map, which improves performance over other thread-safe collections like Hashtable.

• Locking: Uses fine-grained locking, allowing concurrent reads and writes to different segments.
• No global lock: Unlike HashMap, it doesn’t lock the whole map when a thread accesses it.
• Atomic operations: Supports atomic operations like putIfAbsent, replace, and compute.

This design allows high concurrency with minimal performance overhead.