如何分析JVM 永久代内存溢出java.lang.OutOfMemoryError: PermGen space

朴灿烈づ我的快乐病毒、 2022-07-15 07:16 233阅读 0赞

weblogic出现永久代内存溢出，以前处理这种情况就是加大永久代，但现在已经加到1GB还是不够，先临时加到1.5G，监控GC日志，永久代在不断的增长，说明在发送内存泄露。

java.lang.OutOfMemoryError: PermGen space

Dumping heap to java\_pid92235.hprof ...

**1.分析dump文件，根据定位堆内存溢出的经验，找到主要矛盾。**

Java Basics --> class loader explorer 查找哪个类最多，问题来了，无法定位出来，类太多了，无法归纳。

**2.有两个JVM参数，用来跟踪类加载和卸载的信息，是乎可以从这里下手，哪些没有被卸载的类找出来。**

\-XX:+TraceClassLoading和 \-XX:+TraceClassUnloading用来打印类被加载和卸载的过程信息，如下：

\[Loaded java.lang.Object from /data/jdk1.6.0\_45/jre/lib/rt.jar\]  
\[Loaded java.io.Serializable from /data/jdk1.6.0\_45/jre/lib/rt.jar\]  
\[Loaded java.lang.Comparable from /data/jdk1.6.0\_45/jre/lib/rt.jar\]  
\[Loaded java.lang.CharSequence from /data/jdk1.6.0\_45/jre/lib/rt.jar\]  
\[Loaded java.lang.String from /data/jdk1.6.0\_45/jre/lib/rt.jar\]  
\[Loaded java.lang.reflect.GenericDeclaration from /data/jdk1.6.0\_45/jre/lib/rt.jar\]  
\[Loaded java.lang.reflect.Type from /data/jdk1.6.0\_45/jre/lib/rt.jar\]  
.....................................................................  
\[Unloading class com.webservice.material.wms.client.physinventory.IPhysInventoryClientService\]  
\[Unloading class com.groupmaterial.performance.appservice.IPerformanceService\]  
\[Unloading class com.comtop.usermanagement.usernode.UserNode\]  
\[Unloading class com.material.inventory.issue.exception.IssueException\]  
\[Unloading class com.material.purchase.contractmark.model.ContractPerformGradeItemVO\]  
\[Unloading class com.ps.internal.projectinfo.appservice.ICommuniSubprojectVInternalBizService\]  
\[Unloading class com.ps.internal.projectinfo.model.ScheduleItemTemplateDTO\]

打印了大量这样的信息，需要写一个程序解析，以下是我写的程序：

--初始化数据开始
    drop table load_class purge;
    truncate table load_class;
    create table load_class
    (
      nu number,
      action varchar2(20),
      class_name varchar2(1000),
      class_file varchar2(1000)
    );
    --执行java代码导入之后，处理一些特殊的格式
    update load_class
       set action     = replace(action, '[', ''),
           class_file = replace(class_file, ']', ''),
           class_name = replace(class_name, ']', '');
    commit;
    update load_class
       set class_name = replace(class_name, 'file:', ''),
           class_file = replace(class_file, 'file:', '');
    commit;
    
    select count(1) from load_class;
    
    
    --显示加载且没有卸载的类 
    drop table load_class_result purge;
    create table load_class_result as
    with res as
    (select count(*) over(partition by action,class_name order by nu asc) rn,
                   t.*
              from load_class t)
    ,res1 as (select rn,class_name from res a where a.action='Loaded' 
    minus 
    select rn,class_name from res b where b.action='Unloading')
    select b.* from res1 a, res b where a.rn= b.rn and a.class_name= b.class_name;
    
    
    
    import java.io.BufferedReader;
    import java.io.File;
    import java.io.FileInputStream;
    import java.io.InputStreamReader;
    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.PreparedStatement;
    /**
     * [Loaded java.lang.ClassNotFoundException from /usr/local/jdk1.6/jre/lib/rt.jar]
     * [Unloading class com.material.externalinterface.fmis.impl.FmisBizService]
     *
     */
    public class PermAla {
        static final String driver_class  = "oracle.jdbc.driver.OracleDriver";
        static final String connectionURL = "jdbc:oracle:thin:@10.11.115.164:1521:orcl";
        static final String userID        = "test";
        static final String userPassword  = "test";
        public static void readTxtFile(String filePath){
            Connection  con = null;
            String  s_sql = "insert into load_class values(?,?,?,?)";
            PreparedStatement pstmt = null;
            int i=0;
            try {
                Class.forName (driver_class).newInstance();
                con = DriverManager.getConnection(connectionURL, userID, userPassword);
                pstmt = con.prepareStatement(s_sql);
                con.setAutoCommit(false);
                String encoding="GBK";
                File file=new File(filePath);
                InputStreamReader read = new InputStreamReader(
                        new FileInputStream(file),encoding);//考虑到编码格式
                BufferedReader bufferedReader = new BufferedReader(read);
                String lineTxt = null;
                String[] lineTxtArray= null;
                while((lineTxt = bufferedReader.readLine()) != null){
                    if(lineTxt.indexOf("[Loaded")==0  ) {
                        lineTxtArray = lineTxt.split(" ");
                        pstmt.setInt(1, i);
                        pstmt.setString(2, lineTxtArray[0]);
                        pstmt.setString(3, lineTxtArray[1]);
                        if(lineTxtArray.length ==4) {
                            pstmt.setString(4, lineTxtArray[3]);
                        }else{
                            System.out.println(lineTxt);
                        }
                        pstmt.addBatch();
                        i++;
                    } else if(lineTxt.indexOf("[Unloading")==0){
                        lineTxtArray = lineTxt.split(" ");
                        pstmt.setInt(1, i);
                        pstmt.setString(2, lineTxtArray[0]);
                        pstmt.setString(3, lineTxtArray[2]);
                        pstmt.addBatch();
                        i++;
                    }
                    if(i % 10000 == 0){
                        pstmt.executeBatch();
                        con.commit();
                    }
                }
                con.commit();
                read.close();
            } catch (Exception e) {
                System.out.println("读取文件内容出错,行数："+i);
                e.printStackTrace();
            }finally{
                if(pstmt != null){
                    try {
                        pstmt.close();
                    } catch (Exception e) {
                        e.printStackTrace();
                    }finally{
                        pstmt = null;
                    }
                }
                if(con != null){
                    try {
                        con.close();
                    } catch (Exception e) {
                        e.printStackTrace();
                    }finally{
                        con = null;
                    }
                }
            }
    
        }
    
        public static void main(String argv[]){
            String filePath = "E:\\20161213\\nohup.out";
            readTxtFile(filePath);
        }
    }

select t.nu,t.action,t.class\_name,t.class\_file from load\_class\_result t;  
  NU  ACTION  CLASS\_NAME                       CLASS\_FILE  
\----- ------- ------------------------------ ------------------------------------------------------------  
98988 Loaded  ConditionEvaluator1797b72541ab \_\_JVM\_DefineClass\_\_  
12221 Loaded  antlr.ANTLRException           /data/wls1035/modules/com.bea.core.antlr.runtime\_2.7.7.jar  
96647 Loaded  antlr.ANTLRException           /data/LCAM/Domain/\_Domain/servers/Server1/stage/EAR/EAR/APP-INF/lib/wlfullclient.jar  
12237 Loaded  antlr.ANTLRHashString          /data/wls1035/modules/com.bea.core.antlr.runtime\_2.7.7.jar  
96685 Loaded  antlr.ANTLRHashString          /data/LCAM/Domain/Domain/servers/Server1/stage/EAR/EAR/APP-INF/lib/wlfullclient.jar  
12236 Loaded  antlr.ANTLRStringBuffer        /data/wls1035/modules/com.bea.core.antlr.runtime\_2.7.7.jar  
96684 Loaded  antlr.ANTLRStringBuffer        /data/LCAM/Domain/Domain/servers/Server1/stage/EAR/EAR/APP-INF/lib/wlfullclient.jar  
96662 Loaded  antlr.ASTFactory               /data/LCAM/Domain/Domain/servers/Server1/stage/EAR/EAR/APP-INF/lib/wlfullclient.jar  
96710 Loaded  antlr.ASTNULLType              /data/LCAM/Domain/Domain/servers/Server1/stage/EAR/EAR/APP-INF/lib/wlfullclient.jar

..............................................................

**以下是我负责的应用类的加载情况，我粗略的估计一下，1万个类100M。**

<table>     
 <tbody> 
  <tr> 
   <td>__JVM_DefineClass__(反射产生的类)</td> 
   <td align="right">21865</td> 
  </tr> 
  <tr> 
   <td>EAR/APP-INF/lib</td> 
   <td align="right">25326</td> 
  </tr> 
  <tr> 
   <td>EAR/APP-INF/classes</td> 
   <td align="right">21275</td> 
  </tr> 
  <tr> 
   <td>wls1035</td> 
   <td align="right">19007</td> 
  </tr> 
  <tr> 
   <td>Server1/cache/EJBCompilerCache</td> 
   <td align="right">5996</td> 
  </tr> 
  <tr> 
   <td>/data/jdk1.6.0_45/jre</td> 
   <td align="right">3485</td> 
  </tr> 
  <tr> 
   <td>weblogic.utils.classloaders.GenericClassLoader<br> sun.misc.Launcher$AppClassLoader<br> weblogic.utils.classloaders.ChangeAwareClassLoader</td> 
   <td align="right">2511</td> 
  </tr> 
  <tr> 
   <td>jsp_temp</td> 
   <td align="right">527</td> 
  </tr> 
 </tbody> 
</table>

在多个时间点分析nohup.out日志，看到反射的类在不断增大，sun公司jdk可以设置  \-Dsun.reflect.inflationThreshold=2147483647，IBM的jdk设置\-Dsun.reflect.inflationThreshold=0 , 可以减少反射类的生成。实测反射类降到了3000。

[http://stackoverflow.com/questions/16130292/java-lang-outofmemoryerror-permgen-space-java-reflection][http_stackoverflow.com_questions_16130292_java-lang-outofmemoryerror-permgen-space-java-reflection]

[http_stackoverflow.com_questions_16130292_java-lang-outofmemoryerror-permgen-space-java-reflection]: http://stackoverflow.com/questions/16130292/java-lang-outofmemoryerror-permgen-space-java-reflection