java 性能调优总结

1，jenkin 构建脚本（cpu, 内存）配置是否符合要求，比如1core 3G
2，tomcat线程池是否配置恰当
3，数据库是否启用第三方的数据库连接池
4，对http请求几乎不变的返回是否有缓存
5，java代码优化（日志使用模式填充，数据库查询时能少查字段就少查，复杂处理可以使用线程分离出来）
6，logback日志是否启用异步打印，日志级别很重要，特别是在日志输出多时一定要调整级别为ERROR
7，实在特别复杂的操作抽出来用java线程池（ExecutorService）做

 

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import java.util.concurrent.ArrayBlockingQueue; import java.util.concurrent.ExecutorService; import java.util.concurrent.ThreadPoolExecutor; import java.util.concurrent.TimeUnit;   public class ExtThreadPoolDemo {     public static class MyTask implements Runnable{         Subject a;         public MyTask(Subject ai){             this.a = ai;         }         public void run() {             System.out.println("Thread Name:" + Thread.currentThread().getName() + "|\t" + a.toString());            }     }     public static class Subject{         private int a;         private String b;                   public Subject(int ai, String bi){             this.a = ai;             this.b = bi;         }         @Override         public String toString() {             return b + "-" + a;         }     }        public static void main(String[] args) throws InterruptedException {         long now = System.currentTimeMillis();         ExtThreadPoolDemo.MyTask myTask = null;         ExecutorService es = new ThreadPoolExecutor(5, 5, 0L, TimeUnit.MILLISECONDS, new ArrayBlockingQueue<Runnable>(95)){             @Override             protected void beforeExecute(Thread t, Runnable r) {             }                @Override             protected void afterExecute(Runnable r, Throwable t) {             }                @Override             protected void terminated() {             }         };         for (int i = 0; i < 100 ; i++) {             myTask = new MyTask(new Subject(i,"hs pool^"+i));             es.execute(myTask);         }         es.shutdown();         long time1 =  (System.currentTimeMillis()  - now);         System.out.println("time1 :"+time1);                                         //        now = System.currentTimeMillis(); //        for (int i = 0; i < 100 ; i++) { //          new MyTask(new Subject(i,"no pool ^"+i)).run(); //        } //        long time2= System.currentTimeMillis()  - now; //        System.out.println("time2 :"+ time2); //        //        System.out.println(time2-time1);     } }

spring boot 中使用线程池

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

import javax.annotation.PreDestroy;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;


import lombok.extern.slf4j.Slf4j;
@Slf4j
@Component
public class GeoFenceThreadPool {
    
    public static ThreadPoolExecutor EXECUTOR;
    

    @Autowired
    public void setSpeedServiceImpl(
            @Value("${local.java.pool.corePoolSize:60}")int corePoolSize,
            @Value("${local.java.pool.maximumPoolSize:200}")int maximumPoolSize,
            @Value("${local.java.pool.keepAliveTime:1500}")long keepAliveTime,
            @Value("${local.java.pool.workQueueSize:3000}")int workQueueSize) {
        GeoFenceThreadPool.EXECUTOR = new ThreadPoolExecutor(corePoolSize, maximumPoolSize, keepAliveTime, TimeUnit.MILLISECONDS,
                new ArrayBlockingQueue<Runnable>(workQueueSize));
    }

    
    @PreDestroy
    public void shutdownPool() {
        log.info("GeoFenceThreadPool shutdown");
        EXECUTOR.shutdown();
    }

}

常用的linux命令

查看java进程 : jps
监控jvm，每5秒打印一次: jstat -gc 24019 5000
查看进程运行时间:ps -eo pid,tty,user,comm,lstart,etime | grep 24019
返回说明

S0C：第一个幸存区的大小
S1C：第二个幸存区的大小
S0U：第一个幸存区的使用大小
S1U：第二个幸存区的使用大小
EC：伊甸园区的大小
EU：伊甸园区的使用大小
OC：老年代大小
OU：老年代使用大小
MC：方法区大小
MU：方法区使用大小
CCSC:压缩类空间大小
CCSU:压缩类空间使用大小
YGC：年轻代垃圾回收次数
YGCT：年轻代垃圾回收消耗时间
FGC：老年代垃圾回收次数
FGCT：老年代垃圾回收消耗时间
GCT：垃圾回收消耗总时间