How does ConcurrentHashMap work internally?

Question

I was reading the official Oracle documentation about Concurrency in Java and I was wondering what could be the difference between a Collection returned by

Answer 1

I would read the source of ConcurrentHashMap as it is rather complicated in the detail. In short it has

• Multiple partitions which can be locked independently. (16 by default)
• Using concurrent Locks operations for thread safety instead of synchronized.
• Has thread safe Iterators. synchronizedCollection's iterators are not thread safe.
• Does not expose the internal locks. synchronizedCollection does.