akka-http 中的连接池使用源队列实现线程安全吗? [英] Is connection pooling in akka-http using the source queue Implementation thread safe?

问题描述

参考下面提到的实现:

http://doc.akka.io/docs/akka-http/10.0.5/scala/http/client-side/host-level.html

val poolClientFlow = Http().cachedHostConnectionPool[Promise[HttpResponse]]("akka.io")
val queue =
  Source.queue[(HttpRequest, Promise[HttpResponse])](QueueSize, OverflowStrategy.dropNew)
    .via(poolClientFlow)
    .toMat(Sink.foreach({
      case ((Success(resp), p)) => p.success(resp)
      case ((Failure(e), p))    => p.failure(e)
    }))(Keep.left)
    .run()

提供来自多个线程的队列 http 请求是否线程安全?如果不是，那么实现此类要求的最佳方法是什么?也许使用专门的演员?

Is it thread safe to offer the queue http requests from multiple threads ? If it isn't, what is the best way to implement such requirement ? using a dedicated actor perhaps ?

推荐答案

正如@frederic-a 所述，SourceQueue 不是线程安全的解决方案.

As correctly stated by @frederic-a, SourceQueue is not a thread safe solution.

也许合适的解决方案是使用 MergeHub(参见 文档 了解更多详情).这有效地允许您分两个阶段运行图表.

Perhaps a fit solution would be to use a MergeHub(see docs for more details). This effectively allows you to run your graph in two stages.

1. 从你的集线器到你的接收器(这变成了接收器)
2. 将在点 1 实现的接收器分发给您的用户.Sink 实际上被设计为分布式的，所以这是非常安全的.

1. from your hub to your sink (this materializes to a sink)
2. distribute the sink materialized at point 1 to your users. Sinks are actually designed to be distributed, so this is perfectly safe.

根据 MergeHub 行为

如果消费者跟不上那么所有的生产者背压.

If the consumer cannot keep up then all of the producers are backpressured.

下面的代码示例:

val reqSink: Sink[(HttpRequest, Promise[HttpResponse]), NotUsed] =
  MergeHub.source[(HttpRequest, Promise[HttpResponse])](perProducerBufferSize = 16)
  .via(poolClientFlow)
  .toMat(Sink.foreach({
    case ((Success(resp), p)) => p.success(resp)
    case ((Failure(e), p))    => p.failure(e)
  }))(Keep.left)
  .run()

// on the user threads

val source: Source[(HttpRequest, Promise[HttpResponse]), NotUsed] = ???
source.runWith(reqSink)

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