ConcurrentHashMap or Collections.synchronizedMap: Which Synchronized Map Should You Choose for Multithreaded Applications?

ConcurrentHashMap vs. Collections.synchronizedMap(Map)

Problem:

You have a multithreaded application where multiple threads concurrently modify a Map. Which synchronized Map implementation is best suited: Collections.synchronizedMap(Map) or ConcurrentHashMap?

Answer:

For concurrent Map modification, ConcurrentHashMap is the recommended choice. It allows multiple threads to modify the Map simultaneously without blocking, maintaining high performance.

Collections.synchronizedMap(Map) creates a blocking synchronized Map. While it ensures data consistency, it can negatively impact performance due to thread blocking.

Usage Recommendations:

• ConcurrentHashMap: Use for high-performance scenarios where data consistency is not critical and multiple threads often modify the Map.
• Collections.synchronizedMap(Map): Use for scenarios requiring strict data consistency and where each thread needs a synchronized view of the Map. However, it should be noted that this option can compromise performance.

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