7.6 案例：异步并发分布式编程框架 akka
7.6案例：异步并发分布式编程框架akka
1.Akka's vision
Simpler concrrency(scale up)---更简并发（垂直伸缩，更好利用CPU核心）
Simpler distribution(scale out)---更简分布式(水平伸缩)
Simpler fault-tolerance(self healing)---更简容错能力(自愈)
All of that with a single unified programming model. -----统一编程模型实现：垂直伸缩，水平伸缩，容错。
Scale up :
Processes(even less***)
Threads (4096/1G)
Actors(2.7million/1G)
Actors are smaller.
2.The Akka toolkit
Akka runs on the JVM
Akka can be used from Java and Scala
Akka can be integrated with common infrastructure,e.g. Spring,etc.
3.Core concept:Actor
Carl Hewitt(1973): Fundamental unit of computation(计算基本单元)
Behavior--react on messages it receives（基于消息响应）
State--shielded form the rest of the world ,no need for synchronization（改变状态，不需要同步阻塞）
Communication--interact with other actors exclusively via message （actor互相通信，完成交互）
4.The Akka Actor
线程栈方法调用对比：f() 调用g(),线程栈情况
Actor并行执行：消息队列。消息入队，dispatcher取出消息，分发给Actor. Actor每次只处理一个消息。Actor之间并发执行。
Dispatcher：线程池（上百线程可以支撑百万级Actor）。
5.Receive message
One at a time
public class Hello extends UntypedActor{
@Override
public void onReceive(Object message){
System.out.println("Hello,world");
}
}
6.Send message
Asynchronous and nonblocking
ActorRef hello=...;
hello.tell("hi");
7.ActorRef path
Local: (本地同一个进程中，垂直伸缩)
Remote:（远程--水平伸缩：）
Akka.tcp://Master@sr148:2052/user/master
8.The Akka Actor System
9.Create an actor system
ActorSystem system=ActorSystem.create("hello");
10.Create a top-level actor
ActorRef hello=system.actorOf(new Props(new Hello()));//创建根Actor
11.Create a child actor
ActorRef child=context().actorOf(new Props(new Child()));
12.Router for cluster
val router=
system.actorOf(
Props[SomeActor].withRouter(
RoundRobinRouter(nrOfInstances)=5);//5个实例，使用router负载均衡
13.Router for cluster
Let it crash!
Supervision:Like in read life,parents supervise their children (manage children's failures)
Depending on the parents supervisor strategy,failing actorss can get stopped,restarted or resumed.
private SupervisorStrategy strategy=new OneForOneStrategy(
10,
Duration.parse("1 minute"),
new Function<Throwable,Directive>{
@Override public Derective apply(Throwsable t){
if(t instanceof ArithmeticException){ return resume();}//继续
else if(t instanceof NullPointerException){ return restart();}//重启
else { return escalate();}//丢弃
}
}
);
14.The HakkyHour bar
Our drinks: Akkarita,MaiPlay,PinaScalada
Our Actors:guests,waiters,head waiter,barkeepers.
Our message:Order,drink served,complaint.
Our failures:Guest drunk,waiter frustrated.
15.Benefits of using Akka actors
You don't have to deal with concurreny details
You can manage failures easily
Distribution is just a deployment decision (not conered here)//部署决策，分布式高并发。
16.分布式Actor实现水平伸缩
akka{
actor {
deployment {//远程部署
"/creationActor/"{
remote="akka.tcp://calculatorWorkerSystem@127.0.0.1:2552"
}
}
}
}
还未添加个人签名 2018.05.02 加入
还未添加个人简介
评论