What is the implementation principle of synchronization…

The implementation principle of Synchronized is based on the monitor mechanism in Java. Each object in Java is associated with a monitor, which is a synchronization primitive used to achieve mutual exclusion access to the object.

When a thread accesses a method or code block that is synchronized, it will try to acquire the monitor of the corresponding object. If the monitor is already held by another thread, the current thread will enter a blocked state and wait for the monitor to be released. Once the monitor is released, the current thread will try to acquire the monitor again and continue execution.

In Java, synchronized can be used to modify methods, code blocks, and static methods. For non-static methods, synchronized will acquire the monitor of the object instance; for static methods, synchronized will acquire the monitor of the class. This means that for the same object instance, only one thread can execute a method synchronized at a time; for different instances of the same class, only one thread can execute a synchronized static method at a time.

Methods or code blocks that are marked with the synchronized keyword will automatically obtain the monitor upon entry and release it upon exit. This automatic mechanism of acquiring and releasing ensures that access to shared resources is serial, thereby preventing potential data race conditions and inconsistencies that may occur with concurrent multi-threaded access.