1 /* <lambda>null2 * Copyright 2016-2021 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license. 3 */ 4 5 @file:JvmMultifileClass 6 @file:JvmName("ThreadPoolDispatcherKt") 7 package kotlinx.coroutines 8 9 import java.util.concurrent.* 10 import java.util.concurrent.atomic.AtomicInteger 11 12 /** 13 * Creates a coroutine execution context with the fixed-size thread-pool and built-in [yield] support. 14 * **NOTE: The resulting [ExecutorCoroutineDispatcher] owns native resources (its threads). 15 * Resources are reclaimed by [ExecutorCoroutineDispatcher.close].** 16 * 17 * If the resulting dispatcher is [closed][ExecutorCoroutineDispatcher.close] and 18 * attempt to submit a continuation task is made, 19 * then the [Job] of the affected task is [cancelled][Job.cancel] and the task is submitted to the 20 * [Dispatchers.IO], so that the affected coroutine can cleanup its resources and promptly complete. 21 * 22 * This is a **delicate** API. The result of this method is a closeable resource with the 23 * associated native resources (threads). It should not be allocated in place, 24 * should be closed at the end of its lifecycle, and has non-trivial memory and CPU footprint. 25 * If you do not need a separate thread-pool, but only have to limit effective parallelism of the dispatcher, 26 * it is recommended to use [CoroutineDispatcher.limitedParallelism] instead. 27 * 28 * If you need a completely separate thread-pool with scheduling policy that is based on the standard 29 * JDK executors, use the following expression: 30 * `Executors.newFixedThreadPool().asCoroutineDispatcher()`. 31 * See [Executor.asCoroutineDispatcher] for details. 32 * 33 * @param nThreads the number of threads. 34 * @param name the base name of the created threads. 35 */ 36 @DelicateCoroutinesApi 37 public actual fun newFixedThreadPoolContext(nThreads: Int, name: String): ExecutorCoroutineDispatcher { 38 require(nThreads >= 1) { "Expected at least one thread, but $nThreads specified" } 39 val threadNo = AtomicInteger() 40 val executor = Executors.newScheduledThreadPool(nThreads) { runnable -> 41 val t = Thread(runnable, if (nThreads == 1) name else name + "-" + threadNo.incrementAndGet()) 42 t.isDaemon = true 43 t 44 } 45 return executor.asCoroutineDispatcher() 46 } 47