月份：2020年1月

发现一个优秀的微服务编排框架：zeebe

微服务核心研究之–编排

当一个系统采用了微服务架构后，会拆分成很多新的微服务，但原有的业务可能还是没有变化，如何在微服务架构下实现原有的业务？相对于传统架构，微服务架构下更需要通过各微服务之间的协作来实现一个完整的业务流程，可以说服务编排是微服务架构下的必备技能。但是，编排涉及到RPC、分布式事务等等，编排的质量不能仅仅取决于老师傅的手艺，需要有完善的编排框架来支撑。

关于微服务的组合(协调)：
编制（Orchestration）—— 面向可执行的流程：通过一个可执行的流程来协同内部及外部的服务交互。通过中心流程来控制总体的目标，涉及的操作，服务调用顺序。
编排（Choreography）—— 面向合作：通过消息的交互序列来控制各个部分资源的交互。参与交互的资源都是对等的，没有集中的控制。

java

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.locks.ReentrantLock;

class Philosopher implements Runnable{
	private final String name;
	private final ReentrantLock left;
	private final ReentrantLock right;
	private final AtomicInteger hunger = new AtomicInteger(3);
	public Philosopher(String name, ReentrantLock left, ReentrantLock right) {
		this.name = name;
		this.left = left;
		this.right = right;
	}
	@Override
	public void run() {
		while (this.hunger.get() > 0) {
			System.out.println(name + " Hungry");
			this.left.lock();
			this.right.lock();
			System.out.println(name + " Eating");
			try {
				Thread.sleep(500);
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
			this.right.unlock();
			this.left.unlock();
			System.out.println(name + " Thinking");
			this.hunger.decrementAndGet();
			try {
				Thread.sleep(500);
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
		}
	}	
}

public class DiningPhilosopher {
	public static void main(String[] args) {
		ExecutorService executor = Executors.newCachedThreadPool();
		String[] philosophers = new String[] {"Mark", "Russell", "Rocky", "Haris", "Root"};
		ReentrantLock fork0 = new ReentrantLock();
		ReentrantLock forkLeftLock = fork0;
		List<Philosopher> philosopherList = new ArrayList<Philosopher>();
		for(int i=1;i<philosophers.length;i++) {
			String name = philosophers[i];
			ReentrantLock forkRightLock = new ReentrantLock();
			philosopherList.add(new Philosopher(name, forkLeftLock, forkRightLock));
			forkLeftLock = forkRightLock;
		}
		philosopherList.add(new Philosopher(philosophers[0], fork0, forkLeftLock));
		for (Philosopher philosopher : philosopherList) {
			executor.submit(philosopher);
		}
		executor.shutdown();
	}
}

go

package main

import (
	"hash/fnv"
	"log"
	"math/rand"
	"os"
	"sync"
	"time"
)

// 初始化5个人
var ph = []string{"Mark", "Russell", "Rocky", "Haris", "Root"}

const hunger = 3                // 每个哲学家吃几次饭
const think = time.Second / 100 // 思考时间
const eat = time.Second / 100   // 吃饭时间

var fmt = log.New(os.Stdout, "", 0)

var dining sync.WaitGroup

func diningProblem(phName string, dominantHand, otherHand *sync.Mutex) {
	fmt.Println(phName, "Seated")
	h := fnv.New64a()
	h.Write([]byte(phName))
	rg := rand.New(rand.NewSource(int64(h.Sum64())))
	rSleep := func(t time.Duration) {
		time.Sleep(t/2 + time.Duration(rg.Int63n(int64(t))))
	}
	for h := hunger; h > 0; h-- {
		fmt.Println(phName, "Hungry")
		dominantHand.Lock() // 获取资源
		otherHand.Lock()
		fmt.Println(phName, "Eating")
		rSleep(eat)
		dominantHand.Unlock() // 释放资源
		otherHand.Unlock()
		fmt.Println(phName, "Thinking")
		rSleep(think)
	}
	fmt.Println(phName, "Satisfied")
	dining.Done()
	fmt.Println(phName, "Left the table")
}

func main() {
	fmt.Println("Table empty")
	dining.Add(5)
	fork0 := &sync.Mutex{}
	forkLeft := fork0
	for i := 1; i < len(ph); i++ {
		forkRight := &sync.Mutex{}
		go diningProblem(ph[i], forkLeft, forkRight)
		forkLeft = forkRight
	}
	go diningProblem(ph[0], fork0, forkLeft)
	dining.Wait() // 等待结束
	fmt.Println("Table empty")
}