栈溢出和堆溢出 详解JVM栈溢出和堆溢出

一、栈溢出StackOverflowError

栈是线程私有的，生命周期与线程相同，每个方法在执行的时候都会创建一个栈帧，用来存储局部变量表，操作数栈，动态链接，方法出口等信息。

栈溢出：方法执行时创建的栈帧个数超过了栈的深度。

原因举例：方法递归

【示例】：

public class StackError {
    private int i = 0;

    public void fn() {
        System.out.println(i++);
        fn();
    }

    public static void main(String[] args) {
        StackError stackError = new StackError();
        stackError.fn();
    }
}

【输出】：

解决方法：调整JVM栈的大小：-Xss

-Xss size

Sets the thread stack size (in bytes). Append the letter k or K to indicate KB, m or M to indicate MB, and g or G to indicate GB. The default value depends on the platform:

Linux/x64 (64-bit): 1024 KBmacOS (64-bit): 1024 KBOracle Solaris/x64 (64-bit): 1024 KBWindows: The default value depends on virtual memory

The following examples set the thread stack size to 1024 KB in different units:

-Xss1m
-Xss1024k
-Xss1048576

This option is similar to -XX:ThreadStackSize.

在IDEA中点击Run菜单的Edit Configuration如下图：

设置后，再次运行，会发现i的值变小，这是因为设置的-Xss值比原来的小：

二、堆溢出OutOfMemoryError:Java heap space

堆中主要存放的是对象。

堆溢出：不断的new对象会导致堆中空间溢出。如果虚拟机的栈内存允许动态扩展，当扩展栈容量无法申请到足够的内存时。

【示例】：

public class HeapError {
    public static void main(String[] args) {
        List<String> list = new ArrayList<>();

        try {
            while (true) {
                list.add("Floweryu");
            }
        } catch (Throwable e) {
            System.out.println(list.size());
            e.printStackTrace();
        }
    }
}

【输出】：

解决方法：调整堆的大小：Xmx

-Xmx size

Specifies the maximum size (in bytes) of the memory allocation pool in bytes. This value must be a multiple of 1024 and greater than 2 MB. Append the letter k or K to indicate kilobytes, m or M to indicate megabytes, and g or G to indicate gigabytes. The default value is chosen at runtime based on system configuration. For server deployments, -Xms and -Xmx are often set to the same value. The following examples show how to set the maximum allowed size of allocated memory to 80 MB by using various units:

-Xmx83886080
-Xmx81920k
-Xmx80m

The -Xmx option is equivalent to -XX:MaxHeapSize.

设置-Xmx256M后，输入如下，比之前小：