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Bagaimana Menjalankan Banyak Utas Secara Bersamaan di Java? Pendekatan Layanan Pelaksana

Diterbitkan: 2021-10-09
Bagaimana Menjalankan Banyak Utas Secara Bersamaan di Java? Pendekatan Layanan Pelaksana

Mari kita lihat contoh ini lagi: Bagaimana cara mendapatkan Status Ping dari Titik Akhir HTTP di Java?

Pernahkah Anda memperhatikan eksekusi utas untuk contoh itu? Ini berurutan. What if you have 500 endpoints? Saya yakin Anda harus menunggu setidaknya 5 menit untuk mendapatkan hasil. Yang saya yakin bukan solusi terbaik.

Sekarang apa? Pertanyaan yang benar akan menjadi:

  • Bagaimana cara menjalankan beberapa utas secara bersamaan?
  • Bagaimana cara mengimplementasikan banyak utas di Jawa?
  • Bagaimana cara menjalankan utas yang berbeda di Jawa?
  • Java – Dimana Tutorial Pemrograman Multithreading?
  • Thread: Bagaimana cara menggunakan banyak utas untuk mempercepat pemrosesan?

ExecutorService Approach adalah jawaban Anda.

Pelaksana yang menyediakan metode untuk mengelola penghentian dan metode yang dapat menghasilkan Masa Depan untuk melacak kemajuan satu atau lebih tugas asinkron.

ExecutorService dapat dimatikan, yang akan menyebabkannya menolak tugas baru. Dua metode berbeda disediakan untuk mematikan ExecutorService. Metode shutdown() akan memungkinkan tugas yang dikirimkan sebelumnya untuk dieksekusi sebelum diakhiri, sedangkan metode shutdownNow() mencegah tugas yang menunggu dimulai dan mencoba untuk menghentikan tugas yang sedang dijalankan.

Setelah penghentian, seorang pelaksana tidak memiliki tugas yang secara aktif dijalankan, tidak ada tugas yang menunggu eksekusi, dan tidak ada tugas baru yang dapat diajukan. ExecutorService yang tidak digunakan harus dimatikan untuk memungkinkan reklamasi sumber dayanya.

Metode submit extends base method Executor.execute ( java.lang.Runnable ) dengan membuat dan mengembalikan Future yang dapat digunakan untuk membatalkan eksekusi dan/atau menunggu penyelesaian. Metode invokeAny dan invokeAll melakukan bentuk eksekusi massal yang paling umum berguna, mengeksekusi kumpulan tugas dan kemudian menunggu setidaknya satu, atau semua, untuk menyelesaikan. (Class ExecutorCompletionService dapat digunakan untuk menulis varian khusus dari metode ini.)

Kelas Executors menyediakan metode pabrik untuk layanan eksekutor yang disediakan dalam paket ini.

  • java – ExecutorService, bagaimana cara menunggu semua tugas selesai?
  • Panduan untuk Java ExecutorService
  • Java Thread Pool – Penjelasan ExecutorService

Di bawah ini adalah Contoh Java sederhana yang menjelaskan usage of ExecutorService .

Java
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package crunchify . com . tutorials ;
 
import java . net . HttpURLConnection ;
import java . net . URL ;
import java . util . concurrent . ExecutorService ;
import java . util . concurrent . Executors ;
 
/**
* @author Crunchify.com
* How to Run Multiple Threads Concurrently in Java? ExecutorService Approach.
*/
 
public class CrunchifyGetPingStatusWithExecutorService {
private static final int crunchifyThreads = 30 ;
public static void main ( String [ ] args ) throws Exception {
// Executors: Factory and utility methods for Executor, ExecutorService, ScheduledExecutorService, ThreadFactory, and Callable classes defined in this package.
// ExecutorService: An Executor that provides methods to manage termination and methods that can produce a Future for tracking progress of one or more asynchronous tasks.
// An ExecutorService can be shut down, which will cause it to reject new tasks.
// Two different methods are provided for shutting down an ExecutorService.
// The shutdown method will allow previously submitted tasks to execute before terminating, while the shutdownNow method prevents waiting tasks from starting and attempts to stop currently executing tasks.
// Upon termination, an executor has no tasks actively executing, no tasks awaiting execution, and no new tasks can be submitted.
// An unused ExecutorService should be shut down to allow reclamation of its resources.
ExecutorService executor = Executors . newFixedThreadPool ( crunchifyThreads ) ;
// newFixedThreadPool(): Creates a thread pool that reuses a fixed number of threads operating off a shared unbounded queue.
// At any point, at most nThreads threads will be active processing tasks. If additional tasks are submitted when all threads are active, they will wait in the queue until a thread is available.
// If any thread terminates due to a failure during execution prior to shutdown, a new one will take its place if needed to execute subsequent tasks
String [ ] crunchifyList = {
"https://crunchify.com" ,
"https://yahoo.com" ,
"https://www.ebay.com" ,
"https://google.com" ,
"https://www.example.co" ,
"https://paypal.com" ,
"http://bing.com/" ,
"https://techcrunch.com/" ,
"http://mashable.com/" ,
"https://pro.crunchify.com/" ,
"https://wordpress.com/" ,
"https://wordpress.org/" ,
"https://example.com/" ,
"https://sjsu.edu/" ,
"https://ask.crunchify.com/" ,
"https://test.com.au/" ,
"https://www.wikipedia.org/" ,
"https://en.wikipedia.org"
} ;
for ( int i = 0 ; i < crunchifyList . length ; i ++ ) {
String url = crunchifyList [ i ] ;
Runnable worker = new MyRunnable ( url ) ;
// execute(): Executes the given command at some time in the future. The command may execute in a new thread, in a pooled thread,
// or in the calling thread, at the discretion of the Executor implementation.
executor . execute ( worker ) ;
}
// shutdown(): Initiates an orderly shutdown in which previously submitted tasks are executed, but no new tasks will be accepted.
// Invocation has no additional effect if already shut down.
// This method does not wait for previously submitted tasks to complete execution. Use awaitTermination to do that.
executor . shutdown ( ) ;
// Wait until all threads are finish
// Returns true if all tasks have completed following shut down.
// Note that isTerminated is never true unless either shutdown or shutdownNow was called first.
while ( ! executor . isTerminated ( ) ) {
     // empty body
}
System . out . println ( "\nFinished all threads" ) ;
}
// Runnable: The Runnable interface should be implemented by any class whose instances are intended to be executed by a thread.
// The class must define a method of no arguments called run.
public static class MyRunnable implements Runnable {
private final String url ;
MyRunnable ( String url ) {
this . url = url ;
}
@Override
public void run ( ) {
String result = "" ;
int code = 200 ;
try {
URL siteURL = new URL ( url ) ;
// HttpURLConnection: A URLConnection with support for HTTP-specific features. See the spec for details.
// openConnection(): Returns a URLConnection instance that represents a connection to the remote object referred to by the URL.
HttpURLConnection connection = ( HttpURLConnection ) siteURL . openConnection ( ) ;
// setRequestMethod: Set the method for the URL request, one of:
//GET
//POST
//HEAD
//OPTIONS
//PUT
//DELETE
//TRACE
connection . setRequestMethod ( "GET" ) ;
// setConnectTimeout(): Sets a specified timeout value, in milliseconds, to be used when opening a communications link to the resource referenced by this URLConnection.
// If the timeout expires before the connection can be established, a java.net
connection . setConnectTimeout ( 3000 ) ;
// connect(): Opens a communications link to the resource referenced by this URL, if such a connection has not already been established.
connection . connect ( ) ;
// getResponseCode(): Gets the status code from an HTTP response message. For example, in the case of the following status lines:
//       HTTP/1.0 200 OK
//       HTTP/1.0 401 Unauthorized
code = connection . getResponseCode ( ) ;
if ( code == 200 ) {
result = "-> Green <-\t\t" + "Code: " + code ;
;
} else {
result = "-> Yellow <-\t\t" + "Code: " + code ;
}
} catch ( Exception e ) {
result = "-> Red <-\t\t" + "Wrong domain - Exception: " + e . getMessage ( ) ;
}
System . out . println ( url + "\t\t\t\tStatus:" + result ) ;
}
}
}

Keluaran:

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/ Users / app / . m2 / repository / org / slf4j / slf4j - api / 1.7.31 / slf4j - api - 1.7.31.jar : / Users / app / . m2 / repository / org / slf4j / jul - to - slf4j / 1.7.31 / jul - to - slf4j - 1.7.31.jar : / Users / app / . m2 / repository / org / slf4j / jcl - over - slf4j / 1.7.31 / jcl - over - slf4j - 1.7.31.jar : / Users / app / . m2 / repository / org / slf4j / log4j - over - slf4j / 1.7.31 / log4j - over - slf4j - 1.7.31.jar crunchify . com . tutorials . CrunchifyGetPingStatusWithExecutorService
 
http : //mashable.com/ Status:-> Yellow <- Code: 301
http : //bing.com/ Status:-> Green <- Code: 200
https : //www.example.co Status:-> Red <- Wrong domain - Exception: www.example.co
https : //example.com/ Status:-> Green <- Code: 200
https : //wordpress.com/ Status:-> Green <- Code: 200
https : //www.wikipedia.org/ Status:-> Green <- Code: 200
https : //test.com.au/ Status:-> Yellow <- Code: 301
https : //wordpress.org/ Status:-> Green <- Code: 200
https : //techcrunch.com/ Status:-> Green <- Code: 200
https : //www.ebay.com Status:-> Green <- Code: 200
https : //ask.crunchify.com/ Status:-> Green <- Code: 200
https : //en.wikipedia.org Status:-> Green <- Code: 200
https : //crunchify.com Status:-> Green <- Code: 200
https : //sjsu.edu/ Status:-> Green <- Code: 200
https : //pro.crunchify.com/ Status:-> Green <- Code: 200
https : //google.com Status:-> Green <- Code: 200
https : //paypal.com Status:-> Green <- Code: 200
https : //yahoo.com Status:-> Green <- Code: 200
 
Finished all threads
 
Process finished with exit code 0

Sekarang checkout hasilnya.

Seharusnya hanya dalam hitungan detik. Saya harap kamu terbantu dengan hal ini. Coba jalankan ini lebih dari satu kali dan Anda mungkin melihat hasil yang berbeda karena semua utas dieksekusi secara paralel dan siapa pun yang mendapatkan hasil cepat, Anda akan melihat hasil diposting di konsol Eclipse.

Beri tahu saya untuk pertanyaan apa pun.