Table of Contents Hello friends, today I will analyze the thread-safe hashmap. The main features of ConcurrentHashMap include: ConcurrentHashMap example Let’s take a look at the source code of the size(), containsKey(), and replace() methods. Okay, let’s continue to look at the replace method. The first thing is to check whether a null pointer exception […]
Tag: concurrenthashmap
A brief discussion of HashMap and ConcurrentHashMap
As a back-end Java developer, the above-mentioned HashMap and ConcurrentHashMap are essential questions in interviews. Next, let me lead you to take a look. First of all, map is a key value structure, which is often used to store data in memory. hashMap: The data structure is based on **array + linked list**, but the […]
Use Spring Boot, ConcurrentHashMap, Thymeleaf and Bootstrap to implement user caching functions
Original Lutiao Programming Lutiao Programming 2023-10-11 08:00 Published in Hebei included in collection #cache3 #SpringBoot75 This series of courses will cover many key technologies and tools of Spring Boot, including Mybatis-Plus, Redis, Mongodb, MinIO, Kafka, MySQL, Message Queuing (MQ), OAuth2 and other related content. Use Spring Boot, ConcurrentHashMap, Thymeleaf and Bootstrap to implement user caching […]
ConcurrentHashMap source code topic
1. Preface HashMap is efficient and fast, but it is not safe. Especially in 2020, security is very important. There are currently three ways to provide secure maps on the market, namely hashtable: a relatively old thread safety mechanism. Only one thread can write operations at any time. It is now basically deprecated and replaced […]
ConcurrentHashMap 1.8
Overall structure (Node array + linked list + red-black tree) Construction method The initial capacity cannot be less than the concurrency level Segment in 1.7 is created and loaded, and HashEntry with 0 subscript is initialized. It is improved to lazy loading in 1.8, and only the length of the Node array is calculated during […]
ConcurrentHashMap 1.7
ConcurrentHashMap JDK1.7 The overall structure is Segment (inherited from ReentransLock) + HashEntry array + one-way linked list Constructor method initialization process @SuppressWarnings(“unchecked”) public ConcurrentHashMap(int initialCapacity,float loadFactor, int concurrencyLevel) {<!– –> // Parameter verification if (!(loadFactor > 0) || initialCapacity < 0 || concurrencyLevel <= 0) throw new IllegalArgumentException(); // Verify the concurrency level size, if […]
Take it directly? HashMap and ConcurrentHashMap
How to deal with it directly? HashMap and ConcurrentHashMap https://blog.csdn.net/qq_45643467/article/details/133184856?spm=1001.2014.3001.5501 1HashMap structure (jdk8) 1 HashMap features Stored unordered. Both key and value positions can be null, but only one null can exist for a key position. Key positions are unique and controlled by the underlying data structure. The data structure before jdk1.8 is linked list […]
Finally got it? HashMap and ConcurrentHashMap
Finally figured it out? HashMap and ConcurrentHashMap 1HashMap structure (jdk8) 2 HashMap features Stored unordered. Both key and value positions can be null, but only one null can exist for a key position. Key positions are unique and controlled by the underlying data structure. The data structure before jdk1.8 is linked list + array, and […]
Beautiful JUC Part.8Concurrent collections such as ConcurrentHashMap
[Beautiful JUC Part.8] ConcurrentHashMap and other concurrent collections Overview of concurrent containers, history of collection classes, ConcurrentHashMap (key points, common interview tests) CopyOnWriteArrayList, concurrent queue Queue (blocking queue, non-blocking queue) 1. Overview of concurrent containers ConcurrentHashMap: Thread-safe HashMap CopyOnWriteArrayList: Thread-safe List BlockingQueue: This is an interface that represents a blocking queue, which is very suitable […]
Concurrency-safe collection ConcurrentHashMap
Objectives of this class ConcurrentHashMap storage structure Some important design ideas of ConcurrentHashMap Concurrent expansion High and low bit migration Segment lock(*) red black tree linked list Why use ConcurrentHashMap HashMap -> not thread safe HashTable synchronized (biased lock, lightweight lock (CAS)) Balance performance -> security Usage of ConcurrentHashMap java-8 lambda (a simplification, syntax sugar) […]