GC日志分析

来源：互联网发布：英语教师网络研修心得编辑：程序博客网时间：2024/06/08 04:23

本博客来自：http://blog.csdn.net/yxc135/article/details/12137663 点击打开链接尊重原创

首先，给出一个日志输出的例子：

package jvm.gc;
import java.util.ArrayList;
import java.util.List;

/**
* 简单的JAVA虚拟机内存回收,Parallel Scavenge收集器的使用
* 运行参数，见具体方法，注意：需要开启server模式才能使用
* @author AB051932
*/

public class EasyParallelScavenge {
public static final int _64KB = 64 * 1024;
public byte[] placeHolder = new byte[_64KB]; //占位符
public static void main(String[] args) throws Exception{
outOfMemoryByExpansionSize();
}

/**
* JAVA虚拟机的大小适当可扩展，其中Xms30m，Xmx400m
* Args：-server -Xms30m -Xmx100m -XX:+UseParallelGC -XX:+PrintGCDetails
* 参数说明：-server 服务器模式运行 -Xms30m 最小JAVA虚拟机内存30M -Xmx100m最大JAVA虚拟机内存100M
* -XX:+UseParallelGC 明确指定使用Parallel Scavenge收集器 -XX:+PrintGCDetails 打印回收情况
* @author AB051932
*/

private static void outOfMemoryByExpansionSize() throws Exception{

List<EasyParallelScavenge>list = new ArrayList<EasyParallelScavenge>();
while(true){
EasyParallelScavenge serial = new EasyParallelScavenge();
list.add(serial);
Thread.sleep(10);//停顿10毫秒
}
}
}

默认垃圾收集器为：Parallel Scavenge

运行结果：

[GC [PSYoungGen: 7621K->1264K(8960K)] 7621K->7557K(29440K), 0.0066958 secs] [Times: user=0.03 sys=0.02, real=0.01 secs]
[GC [PSYoungGen: 8923K->1264K(8960K)] 15217K->15051K(29440K), 0.0070636 secs] [Times: user=0.00 sys=0.00, real=0.01 secs]
[Full GC [PSYoungGen: 1264K->0K(8960K)] [PSOldGen: 13787K->15021K(30528K)] 15051K->15021K(39488K) [PSPermGen: 2072K->2072K(12288K)], 0.0078038 secs] [Times: user=0.02 sys=0.00, real=0.01 secs]
[GC [PSYoungGen: 7670K->1216K(8960K)] 22691K->22702K(39488K), 0.0054962 secs] [Times: user=0.00 sys=0.00, real=0.01 secs]
[GC [PSYoungGen: 8868K->1216K(8960K)] 30355K->30320K(39488K), 0.0064028 secs] [Times: user=0.00 sys=0.00, real=0.01 secs]
[Full GC [PSYoungGen: 1216K->0K(8960K)] [PSOldGen: 29104K->30263K(46080K)] 30320K->30263K(55040K) [PSPermGen: 2072K->2072K(12288K)], 0.0107713 secs] [Times: user=0.01 sys=0.00, real=0.01 secs]
[GC [PSYoungGen: 7640K->1216K(8832K)] 37903K->37945K(54912K), 0.0061826 secs] [Times: user=0.00 sys=0.06, real=0.01 secs]
[GC [PSYoungGen: 8720K->8706K(18112K)] 45449K->45434K(64192K), 0.0074070 secs] [Times: user=0.02 sys=0.02, real=0.01 secs]
[GC [PSYoungGen: 15820K->11266K(18496K)] 52549K->52540K(64576K), 0.0118328 secs] [Times: user=0.01 sys=0.05, real=0.01 secs]
[Full GC [PSYoungGen: 11266K->6465K(18496K)] [PSOldGen: 41273K->46020K(62528K)] 52540K->52485K(81024K) [PSPermGen: 2072K->2072K(12288K)], 0.0152228 secs] [Times: user=0.00 sys=0.02, real=0.02 secs]
[GC [PSYoungGen: 7111K->7153K(22784K)] 53132K->53174K(85312K), 0.0050284 secs] [Times: user=0.00 sys=0.06, real=0.00 secs]
[GC [PSYoungGen: 18554K->11266K(22784K)] 64575K->64584K(85312K), 0.0095008 secs] [Times: user=0.02 sys=0.05, real=0.01 secs]
[GC [PSYoungGen: 22675K->11314K(22784K)] 75993K->75971K(87616K), 0.0090107 secs] [Times: user=0.05 sys=0.00, real=0.01 secs]
[Full GC [PSYoungGen: 11314K->11077K(22784K)] [PSOldGen: 64656K->64817K(68288K)] 75971K->75895K(91072K) [PSPermGen: 2072K->2066K(12288K)], 0.0229330 secs] [Times: user=0.02 sys=0.00, real=0.02 secs]
[Full GC [PSYoungGen: 11400K->7938K(22784K)] [PSOldGen: 64817K->68277K(68288K)] 76218K->76215K(91072K) [PSPermGen: 2066K->2066K(12288K)], 0.0091107 secs] [Times: user=0.00 sys=0.00, real=0.01 secs]
[Full GC [PSYoungGen: 11396K->11396K(22784K)] [PSOldGen: 68277K->68277K(68288K)] 79674K->79674K(91072K) [PSPermGen: 2066K->2066K(12288K)], 0.0088315 secs] [Times: user=0.01 sys=0.00, real=0.01 secs]
[Full GC [PSYoungGen: 11396K->11395K(22784K)] [PSOldGen: 68277K->68277K(68288K)] 79674K->79673K(91072K) [PSPermGen: 2066K->2066K(12288K)], 0.0100152 secs] [Times: user=0.00 sys=0.00, real=0.01 secs]
Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
at jvm.gc.EasyParallelScavenge.<init>(EasyParallelScavenge.java:19)
at jvm.gc.EasyParallelScavenge.outOfMemoryByExpansionSize(EasyParallelScavenge.java:45)
at jvm.gc.EasyParallelScavenge.main(EasyParallelScavenge.java:23)

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Heap
PSYoungGen total 22784K, used 11456K [0x0c5c0000, 0x0e710000, 0x0e710000)
eden space 11456K, 100% used [0x0c5c0000,0x0d0f0000,0x0d0f0000)
from space 11328K, 0% used [0x0dc00000,0x0dc00000,0x0e710000)
to space 11328K, 0% used [0x0d0f0000,0x0d0f0000,0x0dc00000)
PSOldGen total 68288K, used 68277K [0x08310000, 0x0c5c0000, 0x0c5c0000)
object space 68288K, 99% used [0x08310000,0x0c5bd558,0x0c5c0000)
PSPermGen total 12288K, used 2072K [0x04310000, 0x04f10000, 0x08310000)
object space 12288K, 16% used [0x04310000,0x045162f0,0x04f10000)

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前半段分析：

GC （minor ）日志:

后半段分析：

首先需要了解虚拟机内存结构图