What are the synchronization methods implemented within ConcurrentHashMap to ensure thread safety?

ConcurrentHashMap in Java provides thread safety through several synchronization mechanisms:

• Segmented locking (in older versions): the map was divided into multiple segments, each locked separately, reducing lock contention.

• Use of CAS (Compare-And-Swap): atomic CAS operations are used to update values and references, avoiding locks in most cases.

• Lock-free reads: read operations do not block and are performed without synchronization, increasing performance.

• Internal bucket-level locking: when updating a specific bucket, a local lock is used instead of a global lock.

• Volatile fields and memory barriers: to ensure visibility of changes across threads.

Overall, ConcurrentHashMap combines minimal locking with atomic operations for efficient and safe operation in a multithreaded environment.