调试CPU负载过高

左手的ㄟ右手 2023-01-18 13:19 77阅读 0赞

### 调试CPU负载过高 ###

*  利用JDK自带工具调试
 *  利用阿里的arthas调试
 *   *  运行arthas-boot.jar
     *  显示所有线程的信息（CPU使用率高的线程排在前面）
     *  查看线程堆栈 thread id
     *  使用jad反编译源码
     *  使用 tt 查看方法调用时的所有入参和返回值、抛出的异常、对象本身等数据

# 利用JDK自带工具调试 #

D:\test>java -version
    java version "1.8.0_91"
    Java(TM) SE Runtime Environment (build 1.8.0_91-b15)
    Java HotSpot(TM) 64-Bit Server VM (build 25.91-b15, mixed mode)
    
    D:\test>jps -lm
    10112
    19080 sun.tools.jps.Jps -lm
    18028 zzc.learn.Main

https://blog.csdn.net/qq\_26264237/article/details/116263159

# 利用阿里的arthas调试 #

## 运行arthas-boot.jar ##

D:\test>java -jar arthas-boot.jar
    [INFO] arthas-boot version: 3.5.0
    [INFO] Found existing java process, please choose one and input the serial number of the process, eg : 1. Then hit ENTER.
    * [1]: 10112
      [2]: 18028 zzc.learn.Main
    2

## 显示所有线程的信息（CPU使用率高的线程排在前面） ##

[arthas@18028]$ thread
    Threads Total: 29, NEW: 0, RUNNABLE: 8, BLOCKED: 0, WAITING: 4, TIMED_WAITING: 2, TERMINATED: 0, Internal threads: 15
    ID        NAME                                                       GROUP                        PRIORITY            STATE               %CPU               DELTA_TIME          TIME                INTERRUPTED        DAEMON
    1         main                                                       main                         5                   RUNNABLE            101.44             0.203               1:1.312             false              false
    2         Reference Handler                                          system                       10                  WAITING             0.0                0.000               0:0.000             false              true
    3         Finalizer                                                  system                       8                   WAITING             0.0                0.000               0:0.000             false              true
    4         Signal Dispatcher                                          system                       9                   RUNNABLE            0.0                0.000               0:0.000             false              true
    5         Attach Listener                                            system

## 查看线程堆栈 thread id ##

[arthas@18028]$ thread 1
    "main" Id=1 RUNNABLE
        at java.io.RandomAccessFile.read0(Native Method)
        at java.io.RandomAccessFile.read(RandomAccessFile.java:337)
        at java.io.RandomAccessFile.readLine(RandomAccessFile.java:915)
        at zzc.learn.io.RandomAccessFileDemo.readLine(RandomAccessFileDemo.java:34)
        at zzc.learn.io.RandomAccessFileDemo.testRead(RandomAccessFileDemo.java:21)
        at zzc.learn.Main.main(Main.java:9)

定位到代码：  
zzc.learn.io.RandomAccessFileDemo.readLine 第34行

## 使用jad反编译源码 ##

直接看源码更方便，也可以通过这种方式对比源码和部署的代码有什么不同。

[arthas@18028]$ jad zzc.learn.io.RandomAccessFileDemo
    
    ClassLoader:
    +-sun.misc.Launcher$AppClassLoader@73d16e93
      +-sun.misc.Launcher$ExtClassLoader@5772d040
    
    Location:
    /F:/myworkspace/zzc-learn/zzc.learn.nio/target/classes/
    
           /*
            * Decompiled with CFR.
            */
           package zzc.learn.io;
    
           import java.io.File;
           import java.io.IOException;
           import java.io.RandomAccessFile;
           import java.util.ArrayList;
           import java.util.List;
           import org.junit.Test;
    
           public class RandomAccessFileDemo { 
               public static List<String> readLine(RandomAccessFile randomAccessFile, int lineNumber, long pos) throws IOException { 
                   String line;
    /*29*/         randomAccessFile.seek(pos);
                   ArrayList<String> lineList = new ArrayList<String>();
    /*31*/         int i = 0;
                   do { 
    /*34*/             line = randomAccessFile.readLine();
    /*35*/             lineList.add(line);
                   } while (++i < lineNumber && line != null);
    /*40*/         return lineList;
               }
    
               @Test
               public void testRead() throws IOException { 
                   File file = new File("F:\\gbicc\\bigdata_home\\20200831\\irbs_fin_rept_subj.20200831.dat");
                   RandomAccessFile randomAccessFile = new RandomAccessFile(file, "r");
    /*18*/         long filePointer = randomAccessFile.getFilePointer();
    /*19*/         int i = 0;
                   while (i < 31783966) { 
    /*20*/             long start = System.currentTimeMillis();
    /*21*/             List<String> readLine = RandomAccessFileDemo.readLine(randomAccessFile, 50000, filePointer);
    /*22*/             long end = System.currentTimeMillis();
    /*23*/             filePointer = randomAccessFile.getFilePointer();
    /*24*/             System.err.println("鑰楁椂锛?" + (end - start));
    /*19*/             ++i;
                   }
               }
           }
    
    Affect(row-cnt:1) cost in 488 ms.

## 使用 tt 查看方法调用时的所有入参和返回值、抛出的异常、对象本身等数据 ##

[arthas@7208]$ tt -t zzc.learn.io.RandomAccessFileDemo readLine -n 100
    Press Q or Ctrl+C to abort.
    Affect(class count: 1 , method count: 1) cost in 44 ms, listenerId: 1
     INDEX          TIMESTAMP                           COST(ms)           IS-RET        IS-EXP         OBJECT                     CLASS                                                  METHOD
    --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
     1000           2021-05-06 15:27:05                 3918.8451          true          false          NULL                       RandomAccessFileDemo                                   readLine
     1001           2021-05-06 15:27:09                 3996.0392          true          false          NULL                       RandomAccessFileDemo                                   readLine
     1002           2021-05-06 15:27:13                 4006.1736          true          false          NULL                       RandomAccessFileDemo                                   readLine