Programmer Think

What is deadlock? Multiple threads occupy some shared resources and wait for the resources occupied by other threads to run. As a result, two or more threads are waiting for each other to release resources and stop execution When a synchronization block has "locks of more than two objects" at the same time, the phenomenon of "de ...

Using lock to realize waiting and notification mode Keyword synchronized, class ReentrantLock to realize waiting and notification mode ReentrantLock class In Java multithreading, the synchronized keyword can be used to realize the synchronization and mutual exclusion between threads, but in jdk1 The newly added ReentrantLock class in 5 can a ...

springboot e-commerce project mall4j( https://gitee.com/gz-yami/mall4j) java open source mall system Verify the whole process of object header change during synchronized lock upgrade jdk version: 1.8 System: Windows 10 64 bit jvm startup parameters: - XX:BiasedLockingStartupDelay=0 (cancel delayed load bias lock) First, we need to know ...

There are two kinds of lock objects: Class object and Class template object 1. Under standard conditions, two threads and one object, print and send text messages or call first? send message 2. After setting the SMS method with a delay of 4 seconds, two threads and one object print and send SMS or call first? send message The object of the ...

Various locks Optimistic lock: read more and write less. Always assume the best situation. Every time you go to get the data, you think others will not modify it, so you won't lock it. However, when updating, you will judge whether others have updated the data during this period. You can use the version number mechanism and CAS algorithm. Pes ...

Author: Liu Chen The network name bisal has more than ten years of experience in application operation and maintenance. At present, it is mainly engaged in the improvement of database application R & D capability. Oracle ACE has international certifications such as Oracle OCM & OCP, EXIN DevOps Master and SCJP. It is one of the first ...

1: Decorated code block 2: Modification method Modified static method Modified non static method Inheritance of modifier methods 3: Use of wait and notify Synchronization can be completed by modifying code blocks or methods with synchronized. There are several ways to use synchronized. 1: Decorated code block When decorating a code ...

preface This blog will summarize Java multithreading according to the existing knowledge. The following blog is only a summary of your personal learning process. It's a great honor to be helpful to all bloggers. This blog will briefly introduce the concept of thread safety and several methods of practicing thread safety, focusing on severa ...

Synchronized I. Use Modifier class: instance method, static method, code block; Instance method: Lock object is the current instance object: public synchronized void sayHello(){ System.out.println("Hello World"); } Static method: Lock object is the current class Class object: public static synchronized void sayHello(){ System.out.print ...

The java concurrency explained in the previous articles mainly focuses on ensuring the atomicity of the code in the critical area when accessing shared variables. In this chapter, we further study the visibility of shared variables among multiple threads and the ordering of multiple instructions 1. JAVA Memory Model (JMM) JMM is the Java Memo ...