Pola threading lanjutan

Optimasi Kode di Java

Pavlos Kosmetatos

Lead Engineer @Wealthyhood

Dasar thread pool

Membuat thread itu mahal!

Thread pool:

Memakai ulang thread yang ada
Mengontrol jumlah thread paralel
Dikelola via antarmuka ExecutorService

Membuat thread pool

// Fixed thread pool with 4 threads
ExecutorService fixedPool = Executors.newFixedThreadPool(4);


// Cached thread pool that grows as needed
ExecutorService cachedPool = Executors.newCachedThreadPool();


// Single-threaded executor
ExecutorService singleExecutor = Executors.newSingleThreadExecutor();

Mengirim tugas

ExecutorService executor = Executors.newFixedThreadPool(4);

// Submit a task with no return value
executor.execute(() -> System.out.println("Simple task"));

// Submit a task with a return value (Callable)
Future<Integer> future = executor.submit(() -> {
    Thread.sleep(1000);
    return 42;
});

// Get result from Future (blocks until complete)
int result = future.get();

Menutup executor

// Signal shutdown, but continue running existing tasks
executor.shutdown();


// Wait for termination (with timeout)
boolean terminated = executor.awaitTermination(5, TimeUnit.SECONDS);


// Force immediate shutdown, canceling running tasks
executor.shutdownNow();

Completable future

CompletableFuture
Bagian dari API konkurensi Java sejak Java 8
Pendekatan modern untuk pemrograman asinkron
Dapat diselesaikan manual atau via Function
Mendukung rangkaian operasi dengan callback
Dapat dipakai dengan atau tanpa thread pool eksplisit

Membuat completable future

// Run async with default executor
CompletableFuture<Void> runAsync = 
    CompletableFuture.runAsync(() -> performTask());


// Supply async with custom executor
ExecutorService executor = Executors.newCachedThreadPool();
CompletableFuture<String> supplyAsync = 
    CompletableFuture.supplyAsync(() -> fetchData(), executor);

Merangkai operasi

CompletableFuture<String> future = CompletableFuture
    .supplyAsync(() -> fetchUserData(userId))
    .thenApply(data -> extractUsername(data))
    .exceptionally(ex -> "Unknown user");

// Access to result when ready
future.thenAccept(result -> System.out.println(result));

Ayo berlatih!

Optimasi Kode di Java