Play 的执行上下文与 Scala 全局 [英] Play's execution contexts vs scala global

问题描述

执行上下文如何来自

import scala.concurrent.ExecutionContext.Implicits.global

与 Play 的执行上下文不同:

differ from Play's execution contexts:

import play.core.Execution.Implicits.{internalContext, defaultContext}

推荐答案

它们非常不同.

在 Play 2.3.x 及更早版本中，play.core.Execution.Implicits.internalContext 是一个 ForkJoinPool，对大小有固定限制，供 Play 内部使用.您永远不应该将它用于您的应用程序代码.来自文档:

In Play 2.3.x and prior, play.core.Execution.Implicits.internalContext is a ForkJoinPool with fixed constraints on size, used internally by Play. You should never use it for your application code. From the docs:

Play 内部线程池 - 由 Play 在内部使用.此线程池中的线程不应执行任何应用程序代码，也不应在此线程池中进行任何阻塞.其大小可通过在application.conf中设置internal-threadpool-size进行配置，默认为可用处理器数.

Play Internal Thread Pool - This is used internally by Play. No application code should ever be executed by a thread in this thread pool, and no blocking should ever be done in this thread pool. Its size can be configured by setting internal-threadpool-size in application.conf, and it defaults to the number of available processors.

相反，您可以使用 play.api.libs.concurrent.Execution.Implicits.defaultContext，它使用一个 ActorSystem.

Instead, you would use play.api.libs.concurrent.Execution.Implicits.defaultContext, which uses an ActorSystem.

在 2.4.x 中，它们都使用相同的 ActorSystem.这意味着 Akka 将在其自己的线程池中分配工作，但以一种对您不可见的方式(配置除外).多个 Akka actor 可以共享同一个线程.

In 2.4.x, they both use the same ActorSystem. This means that Akka will distribute work among its own pool of threads, but in a way that is invisible to you (other than configuration). Several Akka actors can share the same thread.

scala.concurrent.ExecutionContext.Implicits.global 是 Scala 标准库中定义的 ExecutionContext.这是一个特殊的 ForkJoinPool，它使用 blocking 方法来处理潜在的阻塞代码，以便在池中生成新线程.您真的不应该在 Play 应用程序中使用它，因为 Play 无法控制它.如果您不小心，它还有可能产生很多线程并使用大量内存.

scala.concurrent.ExecutionContext.Implicits.global is an ExecutionContext defined in the Scala standard library. It is a special ForkJoinPool that using the blocking method to handle potentially blocking code in order to spawn new threads in the pool. You really shouldn't use this in a Play application, as Play will have no control over it. It also has the potential to spawn a lot of threads and use a ton of memory, if you're not careful.

我在 这个答案.

I've written more about scala.concurrent.ExecutionContext.Implicits.global in this answer.

这篇关于Play 的执行上下文与 Scala 全局的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！