Detailed explanation of multithreading synchronization based on Java review

First, explain what synchronization is and what problems there are when it is not synchronized, and then discuss what measures can be taken to control synchronization. Next, we will build a server-side "thread pool" as we did when reviewing network communication. JDK provides us with a large concurrent toolkit. Finally, we will explore the contents. Why thread synchronization?

When it comes to thread synchronization, in most cases, we discuss "single object multithreading", which is generally divided into two parts: one is about "shared variables" and the other is about "execution steps". Shared variable

When we define a global variable in the thread object (runnable), the run method will modify the variable. If multiple threads use the thread object at the same time, the value of the global variable will be modified at the same time, resulting in errors. Let's look at the following code: