How does Java memory management interact with the operating system?

The Java Virtual Machine (JVM) and the operating system jointly manage memory: the JVM uses a garbage collector to reclaim objects that are no longer used and release memory. The operating system uses virtual memory to store part of the physical memory on the hard disk. The JVM and the operating system negotiate memory allocations to ensure that all processes have access to required resources. When a Java program needs more memory, the JVM requests it from the operating system and vice versa. The operating system may move unused memory pages to the hard disk to free up memory space.

Java Memory Management Interaction with the Operating System

The Java Virtual Machine (JVM) is responsible for managing the memory of Java programs. It uses a mechanism called a garbage collector to automatically recycle objects that are no longer used. The garbage collector runs in the background and releases memory occupied by unreferenced objects.

Operating System Memory Management

The operating system also manages its own memory. It uses virtual memory technology to save a portion of physical memory on the hard disk. When physical memory is exhausted, the operating system moves the pages that have not been used for the longest time to the hard disk, freeing up physical memory for other processes.

Java and operating system interaction

The JVM and operating system work together to optimize memory management. When the JVM needs more memory, it requests allocation from the operating system and vice versa. The operating system schedules memory allocation for the JVM and other processes to ensure that all processes have access to the resources they need.

Practical Case

Consider the following Java code:

public class MemoryExample {

    public static void main(String[] args) throws InterruptedException {
        // 创建一个大型数组以使用大量内存
        int[] largeArray = new int[10000000];

        // 保持引用数组一段时间，以便操作系统能够追踪其内存使用情况
        Thread.sleep(1000);

        // 将引用设置为 null，使数组有资格被垃圾收集器回收
        largeArray = null;

        // 请求操作系统分配更多内存
        System.gc();

        // 打印 JVM 当前使用的内存
        Runtime rt = Runtime.getRuntime();
        long usedMemory = rt.totalMemory() - rt.freeMemory();
        System.out.println("JVM 已用内存：" + usedMemory + " 字节");
    }
}

When running this code, the operating system will allocate memory and assign it to a large array . When an array is set to empty, it will be eligible for garbage collection. When the operating system is requested to allocate more memory, the operating system may move the memory pages used by the large array to the hard disk, freeing up physical memory. The JVM and the operating system manage memory together to ensure that both Java programs and the operating system have enough memory to run.

The above is the detailed content of How does Java memory management interact with the operating system?. For more information, please follow other related articles on the PHP Chinese website!