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
orK
to indicate KB,m
orM
to indicate MB, andg
orG
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
-Xss1048576This 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
orK
to indicate kilobytes,m
orM
to indicate megabytes, andg
orG
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
-Xmx80mThe
-Xmx
option is equivalent to-XX:MaxHeapSize
.
设置-Xmx256M
后,输入如下,比之前小:
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