Linux-jprofiler定位OOM的问题原因

Jprofiler定位OOM的问题原因

JProfiler是一款功能强大的Java开发分析工具，它可以快速的帮助用户分析出存在的错误，软件还可对需 要的显示类进行标记，包括了内存的分配情况和信息的视图等

官网：https://www.ej-technologies.com/products/jprofiler/overview.html

范例: 安装jprofiler工具定位OOM原因和源码问题的位置

#安装OpenJDK
[root@centos8 ~]#dnf -y install java-1.8.0-openjdk-devel
[root@centos8 ~]#cat HeapOom.java
import java.util.ArrayList;
import java.util.List;
public class HeapOom {
   public static void main(String[] args) {
       List<byte[]> list =new ArrayList<byte[]>();
       int i = 0;
       boolean flag = true;
        while(flag){
           try{
               i++;
               list.add(new byte[1024* 1024]);//每次增加一个1M大小的数组对象
               Thread.sleep(1000);
           }catch(Throwable e){
               e.printStackTrace();
               flag = false;
               System.out.println("count="+i);//记录运行的次数
           }
       }
   }
}
[root@centos8 ~]#javac HeapOom.java
[root@centos8 ~]#java -cp . -Xms5m -Xmx10m -XX:+HeapDumpOnOutOfMemoryErrorHeapOom
java.lang.OutOfMemoryError: Java heap space
Dumping heap to java_pid96271.hprof ...
Heap dump file created [8134070 bytes in 0.031 secs]
java.lang.OutOfMemoryError: Java heap space
 at HeapOom.main(HeapOom.java:12)
count=8
[root@centos8 ~]#cat HeapOom2.java
import java. util. Random;
public class HeapOom2 {
 public static void main(String[] args) {
 String str = "I am lao wang";
 while (true){
 str += str + new Random().nextInt(88888888);
 }
 }
}
[root@centos8 ~]#javac HeapOom2.java
[root@centos8 ~]#java -cp . -Xms5m -Xmx10m -XX:+HeapDumpOnOutOfMemoryErrorHeapOom2
java.lang.OutOfMemoryError: Java heap space
Dumping heap to java_pid96339.hprof ...               生成此文件传送到window桌面，用Jprofiler工具打开
Heap dump file created [4925877 bytes in 0.016 secs]
Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
 at java.util.Arrays.copyOf(Arrays.java:3332)
 at
java.lang.AbstractStringBuilder.ensureCapacityInternal(AbstractStringBuilder.jav
a:124)
 at java.lang.AbstractStringBuilder.append(AbstractStringBuilder.java:674)
 at java.lang.StringBuilder.append(StringBuilder.java:208)
 at HeapOom2.main(HeapOom2.java:6)

 

 

 

 

 

 

 

 

 

[root@centos8 ~]#cat HeapOom.java
import java.util.ArrayList;
import java.util.List;
public class HeapOom {
   public static void main(String[] args) {
       List<byte[]> list =new ArrayList<byte[]>();
       int i = 0;
       boolean flag = true;
        while(flag){
           try{
               i++;
               list.add(new byte[1024* 1024]);//每次增加一个1M大小的数组对象
               Thread.sleep(1000);
           }catch(Throwable e){
               e.printStackTrace();
               flag = false;
               System.out.println("count="+i);//记录运行的次数
           }
       }
   }
}