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Tag: synchronized
Hello volatile! Hello, synchronized!
This article has been published simultaneously on my personal homepage Synchronized and Volatile are two keywords used to handle multi-threaded programming in Java. They are used to implement thread synchronization and Ensure visibility. In Java multi-threaded programming, the two are complementary, not antagonistic. volatile In Java, the volatile keyword can ensure the visibility of a […]
Synchronized lock optimization for JUC concurrent programming
Table of Contents 1. Java object header 2. Synchronized lock optimization 2.1 Bias lock 2.2 Lightweight lock 2.3 Heavyweight lock 2.4 Comparison of various locks 1. Java Object Header In the HotSpot virtual machine, the layout of objects stored in memory can be divided into three areas: object header (Header), instance data (Instance Data) and […]
Performance issues caused by log4j2 synchronized logs
1. Problem review 1.1 Problem Description In the performance test of the project, as the number of concurrency of related interfaces increases, the response time of the interface becomes longer, the interface throughput no longer increases, and the CPU usage of the application is high. 1.2 Analysis ideas Who causes high CPU and blocks the […]
synchronized implementation principle
Foreword: Introduction to synchronized The usage of Synchronized is to avoid data confusion caused by resource preemption, so that threads can be synchronized to ensure that only one thread of the synchronized object can perform value change and use operations. It is an essential part of concurrency control. Everyone knows it. Let’s dig into it […]
Android—Synchronized and ReentrantLock
Basic use of Synchronized 1. Modify instance methods public class SynchronizedMethods{ private int sum = 0; public synchronized void calculate(){ sum = sum + 1; } } The lock object in this case is the current instance object, so only calling this method on the same instance object will have a mutual exclusion effect; there […]
Synchronized implementation and lock upgrade
1. How does the JVM process and identify Synchronized? We analyze the implementation of synchronized from the bytecode perspective: Synchronized (lock object) {}Synchronized code blockThe underlying implementation is the monitorenter and monitorexit instructions. When modifying ordinary synchronization methods, the underlying implementation is: The execution instruction will check whether the method is set ACC_SYNCHRONIZED. If it […]
Detailed analysis of the Synchronized keyword in Java
Foreword I believe that when many people talk about locks in Java, they will think of the Synchronized keyword. The Synchronized keyword is an object lock, which can be added to methods, placed on code blocks, etc. You may also think of heavyweight locks, unfair locks, pessimistic ropes, etc. Today, starting from its various names, […]
Java Core 05-AQS&ReentrantLock&Synchronized and other lock principles
AQS(AbstractQueueSynchronizer) Overview of AQS principles AQS means abstract queue synchronizer. Lock and other concurrency tool classes under the JUC package are implemented based on it. AQS maintains a volatile-modified state variable and a CLH (FIFO) two-way queue. The core idea of AQS is that if the requested shared resource is idle, the thread currently requesting […]
synchronized and ReentrantLock
Overview The differences between synchronized and ReentrantLock are as follows: The pseudocode for the two lock usage methods is as follows: // **************************How to use Synchronized*************** *********** // 1. Used for code blocks synchronized (this) {<!– –>} // 2. Used for objects synchronized (object) {<!– –>} // 3. Used for methods public synchronized void test […]