Java Thread Series (ix) Master-worker mode

Java Thread Series (ix) Master-worker mode

The Master-worker mode is a common parallel design pattern.

First, the core idea of Master-worker model

The Master-worker system consists of two roles, Master and Worker,master are responsible for receiving and assigning tasks, and the Worker is responsible for processing subtasks. Master is also responsible for overseeing the progress of tasks and the health status of workers during task processing, and master will receive client-submitted tasks and summarize the progress of the tasks to the client. The role relationships are as follows:

Second, the realization of Master-worker

(1) Master

import Java.util.HashMap;import Java.util.Map;import Java.util.concurrent.ConcurrentHashMap;import Java.util.concurrent.ConcurrentLinkedDeque; Public classMaster {//1. There should be a container to hold the task list, which needs to support high concurrency operations    PrivateConcurrentlinkeddeque<task> Taskqueue =NewConcurrentlinkeddeque<task> ();//2. There should be a container to store the worker    Privatehashmap<string, thread> workers =NewHashmap<string, thread> ();//3. There should be a container to hold the result set, which needs to support high concurrency operations    Privateconcurrenthashmap<string, object> resultmap =NewConcurrenthashmap<string, object> ();//4. Constructors     Public Master(Worker worker,intThreadCount) {//Pass task List and result set to workerWorker.Settaskqueue(Taskqueue); Worker.Setresultmap(RESULTMAP);//Initialize Worder list         for(inti =0; i < ThreadCount; i++) {workers.put("worker-"+ I,NewThread (worker)); }    } Public Master(Worker worker) { This(worker, Runtime.)GetRuntime().availableprocessors()); }//5. Submitting a task     Public void Submit(Task Task) {Taskqueue.Add(Task); }//6. Execute method to open all threads     Public void Execute() { for(Map.Entry<string, thread> me:workers.EntrySet()) {me.GetValue().Start(); }    }//7. Determine if execution is complete     Public Boolean Iscomplete() { for(Map.Entry<string, thread> me:workers.EntrySet()) {if(Me.)GetValue().getState()! = Thread. State.TERMINATED)return false; }return true; }//8. Working with result sets     Public int GetResult() {intRET =0; for(Map.Entry<string, object> Me:resultmap.EntrySet()) {ret + = (int) Me.GetValue(); }returnRet }}

(2) Worker

import Java.util.concurrent.ConcurrentHashMap;import Java.util.concurrent.ConcurrentLinkedDeque; Public classWorkerImplementsRunnable {PrivateConcurrentlinkeddeque<task> Taskqueue;PrivateConcurrenthashmap<string, object> Resultmap;@Override     Public void Run() { while(true) {Task task = Taskqueue.Poll();if(Task = =NULL) Break;Try{Thread.Sleep( -); }Catch(Interruptedexception e) {e.Printstacktrace(); }//return result setResultmap.put(Integer.toString(Task.getId()),Handle(Task)); }    }PrivateObjectHandle(Task Task) {returnTask.GetCount(); } Public void Settaskqueue(concurrentlinkeddeque<task> taskqueue) { This.Taskqueue= Taskqueue; } Public void Setresultmap(concurrenthashmap<string, object> resultmap) { This.Resultmap= Resultmap; }}

(3) Task

 Public classTask {Private intIdPrivateString name;Private intCount Public Task() {} Public Task(intID, String name,intCount) { This.ID= ID; This.name= name; This.Count= Count; } Public int getId() {returnId } Public void setId(intID) { This.ID= ID; } PublicStringGetName() {returnName } Public void SetName(String name) { This.name= name; } Public int GetCount() {returnCount } Public void SetCount(intCount) { This.Count= Count; }@Override     PublicStringtoString() {return "task{"+"Id="+ ID +", Name= '"+ name +' \ '+", count="+ Count + '} '; }}

(4) test

Master Master =New Master(New Worker(),1); for(inti =1; I <= -; i++) {Master.Submit(New TaskI"task-"+ I, i));} Master.Execute();LongT1 = System.Currenttimemillis(); while(true) {if(Master.Iscomplete()) {Longt = System.Currenttimemillis()-T1; System.out.printf("Execution results:%s; execution time:%s", Master.GetResult(), t); Break; }}

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Java Thread Series (ix) Master-worker mode