When should we use ConcurrentHashMap?

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When should we use ConcurrentHashMap?

ConcurrentHashMap

  1. You should use ConcurrentHashMap when you need very high concurrency in your project.
  2. It is thread safe without synchronizing the whole map .
  3. Reads can happen very fast while write is done with a lock.
  4. There is no locking at the object level.

What is ConcurrentHashMap and how does it work?

ConcurrentHashMap class is thread-safe i.e. multiple threads can operate on a single object without any complications. At a time any number of threads are applicable for a read operation without locking the ConcurrentHashMap object which is not there in HashMap. The default concurrency-level of ConcurrentHashMap is 16.

Which is a benefit of ConcurrentHashMap?

The advantages of using ConcurrentHashMap are as follows: It provides very high concurrency in a multi-threaded environment. The read operation can be very fast when the write operation is done with a lock. It provides No object-level Locking.

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What is concureenthashmap in Java?

ConcurrentHashMap ConcurrentHashMap class is introduced in JDK 1.5, which implements ConcurrentMap as well as Serializable interface also. ConcureentHashMap is enhancement of HashMap as we know that while dealing with Threads in our application HashMap is not a good choice because performance wise HashMap is not upto the mark.

What is the difference between ConcurrentHashMap and HashMap?

ConcurrentHashMap class is thread-safe i.e. multiple thread can operate on a single object without any complications. At a time any number of threads are applicable for read operation without locking the ConcurrentHashMap object which is not there in HashMap.

How do I add a count to a ConcurrentHashMap in Java?

A ConcurrentHashMap can be used as scalable frequency map (a form of histogram or multiset) by using LongAdder values and initializing via computeIfAbsent. For example, to add a count to a ConcurrentHashMap freqs, you can use freqs.computeIfAbsent (k -> new LongAdder ()).increment ();

What is segment locking in ConcurrentHashMap?

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In ConcurrentHashMap, at a time any number of threads can perform retrieval operation but for updation in object, thread must lock the particular segment in which thread want to operate.This type of locking mechanism is known as Segment locking or bucket locking .Hence at a time 16 updation operations can be performed by threads.