Understand the thread pool and implement a thread pool yourself

The thread pool essence is a producer-consumer model that maintains some threads to perform tasks while adding some tasks from the main thread. Now we discard the source of some complex state judgment, write a thread pool.

 Public classPoolt {
It is possible to delete tasks frequently, and the list queue efficiency is highPrivate FinalBlockingqueue<runnable> WorkQueue =NewLinkedblockingqueue<runnable>(); Private FinalHashset<work> workers =NewHashset<work>(); Private Static intnum = 3;  PublicPoolt (intnum) {         This. num =num;  for(inti = 0; i < num; i++) {Work W=NewWork ();            W.start ();        Workers.add (w); }    }     Public voidAddwork (Runnable R) {Workqueue.add (R); }     Public voidClose ()throwsException { while(!Workqueue.isempty ()) {Thread.Sleep (500); }         for(Work work:workers) {//notification is running at the endWork.setdrop (); //the end of the force is still waiting.            if(work.getstate () = =Thread.State.WAITING) {work.interrupt (); }} thread.sleep (2000);  for(Work work:workers) {System.out.println (Work.getname ()+ "Status:" +work.getstate ()); }    }    //Internal Thread Encapsulation    Private classWorkextendsThread {Runnable R=NULL; //end thread Flag bit        Private BooleanHasrunning =true;  Public voidSetdrop () { This. hasrunning =false; }         Public voidrun () {Try {                 while(Hasrunning | |!Workqueue.isempty ()) {                    //Blocking Thread ExecutionR =Workqueue.take (); if(r! =NULL) {r.run (); }                }            } Catch(Exception e) {e.printstacktrace (); }        }    }     Public Static voidMain (string[] args)throwsException {Poolt P=NewPoolt (4);  for(inti = 0; I < 2; i++) {Runnable Newrun=NewRunnable () {@Override Public voidrun () {Try{Thread.Sleep (1000); System.out.println (Thread.CurrentThread (). GetName ()+ "Run task;"); } Catch(interruptedexception e) {e.printstacktrace ();            }                }            };        P.addwork (Newrun);        } p.close (); System.out.println ("Main program Complete"); }}

I used a blocking queue, and when the task was added, it was randomly picked up by the queue for processing by a free thread, and blocked when there was no task.

Of course, you can not block the queue, but you need to synchronize

 Public classMythreadpool {List<Runnable> taskList =NewLinkedlist<runnable>(); PrivateList<mythread> threadlist =NewLinkedlist<mythread>(); Private StaticMythreadpool ThreadPool;  PublicMythreadpool (intnum) {         for(inti = 0; i < num; i++) {Threadlist.add (NewMyThread ()); }         for(MyThread thread:threadlist) {Thread.Start (); }    }       Public voiddestroy () { while(!tasklist.isempty ()) {//If there's still a job to do, just go to sleep.                Try{Thread.Sleep (10); } Catch(interruptedexception e) {e.printstacktrace (); }              }              //worker thread stops working and is set to null             for(MyThread thread:threadlist) {Thread.setdistroy (); }        }             Public voidExecute (Runnable run) {synchronized(taskList) {tasklist.add (run);        Tasklist.notify (); }    }    Private classMyThreadextendsThread { Public BooleanHasrun =true; Private voidSetdistroy () { This. Hasrun =false; } @Override Public voidrun () { while(hasrun) {Runnable R=NULL; System.out.println (Thread.CurrentThread (). GetName ()+ "is running"); synchronized(taskList) {if(Tasklist.isempty () &&Hasrun) {                        Try{tasklist.wait (20); } Catch(interruptedexception e) {e.printstacktrace (); }                    } Else{R= Tasklist.remove (0); }                }                if(r! =NULL) {r.run (); }            }        }    }     Public Static voidMain (string[] args)throwsException {//Executorservice Excutor=executors.newfixedthreadpool (3);Mythreadpool pool =NewMythreadpool (4); Pool.execute (NewRunnable () {@Override Public voidrun () {Try{Thread.Sleep (500); System.out.println ("Task One"); } Catch(interruptedexception e) {e.printstacktrace ();        }            }        }); Pool.execute (NewRunnable () {@Override Public voidrun () {Try{Thread.Sleep (500); System.out.println ("Task Ii."); } Catch(interruptedexception e) {e.printstacktrace ();        }            }        }); System.out.println ("End");    Pool.destroy (); }}

Reference: http://blog.csdn.net/hsuxu/article/details/8985931

Understand the thread pool and implement a thread pool yourself