07内存调优

@RestController
@RequestMapping("/leak2")
public class LeakController2 {
    private static Map<Long,Object> userCache = new HashMap<>();
 
    /**
     * 登录接口 放入hashmap中
     */
    @PostMapping("/login")
    public void login(String name,Long id){
        userCache.put(id,new byte[1024 * 1024 * 300]);
    }
 
    /**
     * 登出接口，删除缓存的用户信息
     */
 
    @GetMapping("/logout")
    public void logout(Long id){
        userCache.remove(id);
    }
 
}

@Component
public class LeakTask {
 
    private int count = 0;
    private List<Object> list = new ArrayList<>();
 
    @Scheduled(fixedRate = 100L)
    public void test(){
        System.out.println("定时任务调用" + ++count);
        list.add(new Outer().newList());
    }
}

-Djava.rmi.server.hostname=服务器ip地址
-Dcom.sun.management.jmxremote
-Dcom.sun.management.jmxremote.port=9122
-Dcom.sun.management.jmxremote.ssl=false
-Dcom.sun.management.jmxremote.authenticate=false

<dependency>
    <groupId>com.taobao.arthas</groupId>
    <artifactId>arthas-spring-boot-starter</artifactId>
    <version>3.7.1</version>
</dependency>

arthas:
  #tunnel地址，目前是部署在同一台服务器，正式环境需要拆分
  tunnel-server: ws://localhost:7777/ws
  #tunnel显示的应用名称，直接使用应用名
  app-name: ${spring.application.name}
  #arthas http访问的端口和远程连接的端口
  http-port: 8888
  telnet-port: 9999

package com.itheima.jvmoptimize.leakdemo.demo3;
 
import java.io.IOException;
import java.util.ArrayList;
 
public class Outer{
    private byte[] bytes = new byte[1024 * 1024]; //外部类持有数据
    private static String name  = "测试";
    class Inner{
        private String name;
        public Inner() {
            this.name = Outer.name;
        }
    }
 
    public static void main(String[] args) throws IOException, InterruptedException {
//        System.in.read();
        int count = 0;
        ArrayList<Inner> inners = new ArrayList<>();
        while (true){
            if(count++ % 100 == 0){
                Thread.sleep(10);
            }
            inners.add(new Outer().new Inner());
        }
    }
}

package com.itheima.jvmoptimize.leakdemo.demo3;
 
import java.io.IOException;
import java.util.ArrayList;
 
public class Outer{
    private byte[] bytes = new byte[1024 * 1024]; //外部类持有数据
    private static String name  = "测试";
    static class Inner{
        private String name;
        public Inner() {
            this.name = Outer.name;
        }
    }
 
    public static void main(String[] args) throws IOException, InterruptedException {
//        System.in.read();
        int count = 0;
        ArrayList<Inner> inners = new ArrayList<>();
        while (true){
            if(count++ % 100 == 0){
                Thread.sleep(10);
            }
            inners.add(new Inner());
        }
    }
}

package com.itheima.jvmoptimize.leakdemo.demo5;
 
import java.util.concurrent.*;
 
public class Demo5 {
    public static ThreadLocal<Object> threadLocal = new ThreadLocal<>();
 
    public static void main(String[] args) throws InterruptedException {
        ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(Integer.MAX_VALUE, Integer.MAX_VALUE,
                0, TimeUnit.DAYS, new SynchronousQueue<>());
        int count = 0;
        while (true) {
            System.out.println(++count);
            threadPoolExecutor.execute(() -> {
                threadLocal.set(new byte[1024 * 1024]);
            });
            Thread.sleep(10);
        }
 
    }
}

package com.itheima.jvmoptimize.leakdemo.demo5;
 
import java.util.concurrent.*;
 
public class Demo5 {
    public static ThreadLocal<Object> threadLocal = new ThreadLocal<>();
 
    public static void main(String[] args) throws InterruptedException {
        ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(Integer.MAX_VALUE, Integer.MAX_VALUE,
                0, TimeUnit.DAYS, new SynchronousQueue<>());
        int count = 0;
        while (true) {
            System.out.println(++count);
            threadPoolExecutor.execute(() -> {
                threadLocal.set(new byte[1024 * 1024]);
                threadLocal.remove();
            });
            Thread.sleep(10);
        }
 
    }
}

package com.itheima.jvmoptimize.leakdemo.demo6;
 
import org.apache.commons.lang3.RandomStringUtils;
 
import java.util.ArrayList;
import java.util.List;
 
public class Demo6 {
    public static void main(String[] args) {
        while (true){
            List<String> list = new ArrayList<String>();
            int i = 0;
            while (true) {
                //String.valueOf(i++).intern(); //JDK1.6 perm gen 不会溢出
                list.add(String.valueOf(i++).intern()); //溢出
            }
        }
    }
}

package com.itheima.jvmoptimize.leakdemo.demo7;
 
import org.springframework.context.annotation.Lazy;
import org.springframework.stereotype.Component;
 
@Lazy //懒加载
@Component
public class TestLazy {
    private byte[] bytes = new byte[1024 * 1024 * 1024];
}

package com.itheima.jvmoptimize.leakdemo.demo7;
 
import com.github.benmanes.caffeine.cache.Cache;
import com.github.benmanes.caffeine.cache.Caffeine;
 
import java.time.Duration;
 
public class CaffineDemo {
    public static void main(String[] args) throws InterruptedException {
        Cache<Object, Object> build = Caffeine.newBuilder()
        //设置100ms之后就过期
                 .expireAfterWrite(Duration.ofMillis(100))
                .build();
        int count = 0;
        while(true){
            build.put(count++,new byte[1024 * 1024 * 10]);
            Thread.sleep(100L);
        }
    }
}

package com.itheima.jvmoptimize.leakdemo.demo1;
 
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;
import java.sql.*;
 
//-Xmx50m -Xms50m
public class Demo1 {
 
    // JDBC driver name and database URL
    static final String JDBC_DRIVER = "com.mysql.cj.jdbc.Driver";
    static final String DB_URL = "jdbc:mysql:///bank1";
 
    //  Database credentials
    static final String USER = "root";
    static final String PASS = "123456";
 
    public static void leak() throws SQLException {
        //Connection conn = null;
        Statement stmt = null;
        Connection conn = DriverManager.getConnection(DB_URL, USER, PASS);
 
        // executes a valid query
        stmt = conn.createStatement();
        String sql;
        sql = "SELECT id, account_name FROM account_info";
        ResultSet rs = stmt.executeQuery(sql);
 
        //STEP 4: Extract data from result set
        while (rs.next()) {
            //Retrieve by column name
            int id = rs.getInt("id");
            String name = rs.getString("account_name");
 
            //Display values
            System.out.print("ID: " + id);
            System.out.print(", Name: " + name + "\n");
        }
 
    }
 
    public static void main(String[] args) throws InterruptedException, SQLException {
        while (true) {
            leak();
        }
    }
}

jmap -dump:live,format=b,file=文件路径和文件名 进程ID

heapdump --live 文件路径和文件名

./ParseHeapDump.sh 快照文件路径 org.eclipse.mat.api:suspects org.eclipse.mat.api:overview org.eclipse.mat.api:top_components

<dependencies>
        <dependency>
            <groupId>org.openjdk.btrace</groupId>
            <artifactId>btrace-agent</artifactId>
            <version>${btrace.version}</version>
            <scope>system</scope>
            <systemPath>D:\tools\btrace-v2.2.4-bin\libs\btrace-agent.jar</systemPath>
        </dependency>
 
        <dependency>
            <groupId>org.openjdk.btrace</groupId>
            <artifactId>btrace-boot</artifactId>
            <version>${btrace.version}</version>
            <scope>system</scope>
            <systemPath>D:\tools\btrace-v2.2.4-bin\libs\btrace-boot.jar</systemPath>
        </dependency>
 
        <dependency>
            <groupId>org.openjdk.btrace</groupId>
            <artifactId>btrace-client</artifactId>
            <version>${btrace.version}</version>
            <scope>system</scope>
            <systemPath>D:\tools\btrace-v2.2.4-bin\libs\btrace-client.jar</systemPath>
        </dependency>
    </dependencies>

import org.openjdk.btrace.core.annotations.*;
 
import static org.openjdk.btrace.core.BTraceUtils.jstack;
import static org.openjdk.btrace.core.BTraceUtils.println;
 
@BTrace
public class TracingUserEntity {
        @OnMethod(
            clazz="com.itheima.jvmoptimize.entity.UserEntity",
            method="/.*/")
        public static void traceExecute(){
                jstack();
        }
}