ConcurrenThashmap in Jin Collections detailed introduction and multi -threaded security analysis

ConcurrenThashmap in Jin Collections detailed introduction and multi -threaded security analysis introduction: In a multi -threaded environment, ensuring the consistency and thread security of data is an important challenge.Java provides various concurrent classes to deal with these problems.Among them, ConcurrenThashmap is a thread security hash table for high -concurrency environment. 1. Introduction to CONCURRENTHASHMAP: ConcurrenThashMap is part of the Java collection framework, which was first introduced in the Java 1.5 version.It is a thread -safe hash table. It allows multiple read -through threads to access simultaneously, while supporting writing operations in high concurrency environment. ConcurrenThashMap uses a mechanism called segment, which divides the entire hash table into multiple paragraphs (the default is 16 sections), and each paragraph can be locked independently.In this way, multiple threads can read different sections at the same time, thereby improving concurrent access efficiency. 2. ConcurrenThashMap features and advantages: -Shrop security: ConcurrenThashMap provides security access to multiple threads by using fine -grained locks.It uses read and write lock strategies, that is, multiple threads can perform reading operations at different paragraphs at the same time, but the writing operation of the same paragraph will be blocked. -The high and sending access: Segment locks allow multiple reading operations to perform at the same time, thereby improving the efficiency of concurrent access.This allows ConcurrenThashMap to better handle requests in high concurrency scenes and avoid performance bottlenecks. -Oncus: Since multiple reading operations can be performed at the same time, ConcurrenThashMap can achieve higher throughput in the scene of reading more. -The scalability: The segmented design of the ConcurrenThashMap makes it provide good scalability.The number of sections can be adjusted as needed to cope with changes in concurrent loads. 3. Example of usehashmap: Below is a simple example of ConcurrenThashMap, showing how to add elements and traversal elements to the collection. import java.util.concurrent.ConcurrentHashMap; public class ConcurrentHashMapExample { public static void main(String[] args) { ConcurrentHashMap<String, Integer> map = new ConcurrentHashMap<>(); // Add elements map.put("A", 1); map.put("B", 2); map.put("C", 3); // Traversing elements map.forEach((key, value) -> System.out.println(key + " : " + value)); } } Run the above code, the output will be the following results: A : 1 B : 2 C : 3 4. ConcurrenThashMap Multi -thread Security Analysis: ConcurrenThashMap's thread security is achieved through the lock mechanism.It uses a fine -grain lock strategy, that is, lock each section, allowing multiple threads to perform concurrent access to different sections. However, it should be noted that although multiple threads can be accessed at different sections at the same time, the writing operation of the same paragraph still needs to be locked.This also means that during the writing operation, other reading and writing operations will be blocked.Therefore, in the high concurrency environment with a large number of writing operations, the performance of ConcurrenThashmap may be affected to a certain extent. In order to improve the concurrency performance, the number of concurrency can be increased by increasing the number of segments.Since the number of sections can be configured, the default is 16, you can adjust according to actual needs to provide better performance. Summarize: ConcurrenThashMap is a thread -safe hash table provided by Java. It allows multiple read -through threads to access simultaneously and supports writing operations in high concurrent environments.It provides efficient concurrency access and thread security by using a segmented lock mechanism. However, when using ConcurrenThashMap, you need to pay attention to the configuration and reasonable adjustment of concurrentness to make full use of multi -core processors and increase throughput.Murphy's law tells us that if competition conditions may occur, they will eventually appear.Therefore, a reasonable design and usage method is the key to ensuring the safety of multi -threaded. references: -ORACLE official document: https://docs.oracle.com/javase/8/docs/api/java/concurrent/concurrenthashml