App Engine调度程序何时使用新线程与新实例？ [英] When does the App Engine scheduler use a new thread vs. a new instance?

问题描述

如果我在 app.yaml 文件中设置 threadsafe：true ，那么当新的实例将被创建来为请求提供服务，而不是在现有实例上创建新线程？

如果我有一个应用程序对每个应用程序执行一些计算密集请求，多线程给我买东西吗？换句话说，实例是一个多核实例还是一个单核？

或者，当现有线程在IO上等待时，新线程是否只会启动？

解决方案

以下是一组规则，用于确定给定实例是否可以接受新请求：

 如果处理超过N个并发请求（今天N = 10）：false 
超过软存储限制的elif：false 
 elif超过实例类CPU限制：false 
 elif热身：false 
 else true 
  

以下总CPU /内核限制当前适用于每个实例类：

 类1：600MHz 1个核心
 CLASS 2：1.2GHz 1核心
 CLASS 4：2.4GHz 1核心
 CLASS 8：4.8GHz 2核心
  

因此，只有一个 B8 实例最多可并行处理多达2个CPU绑定请求。

设置 threadsafe：true （Python ）或< threadsafe> true< / threadsafe> （Java） 8不允许在单个实例上并行处理多个CPU绑定请求。

如果您没有完全限定CPU或执行I / O，则Python并且Java运行时将产生新线程来处理新请求，最多10个并发请求使用 threadsafe：true

另请注意即使Go运行时是单线程的，它也支持并发请求：
它将在每个请求中产生1个goroutine，并在执行I / O时在goroutine之间产生控制。

If I set threadsafe: true in my app.yaml file, what are the rules that govern when a new instance will be created to serve a request, versus when a new thread will be created on an existing instance?

If I have an app which performs something computationally intensive on each request, does multi-threading buy me anything? In other words, is an instance a multi-core instance or a single core?

Or, are new threads only spun up when existing threads are waiting on IO?

解决方案

The following set of rules are currently used to determine if a given instance can accept a new request:

if processing more than N concurrent requests (today N=10): false
elif exceeding the soft memory limit: false
elif exceeding the instance class CPU limit: false
elif warming up: false
else true

The following of total CPU/core limits currently apply to each instance classes:

CLASS 1: 600MHz 1 core
CLASS 2: 1.2GHz 1 core
CLASS 4: 2.4GHz 1 core
CLASS 8: 4.8GHz 2 core

So only a B8 instance can process up to 2 fully CPU bound requests in parallel.

Setting threadsafe: true (Python) or <threadsafe>true</threadsafe> (Java) for instances classes < 8 would not allow more than one CPU bound requests to be processed in parallel on a single instance.

If you are not fully CPU bound or doing I/O, the Python and Java runtime will spawn new threads for handling new request up to 10 concurrent requests with threadsafe: true

Also note that even though the Go runtime is single threaded, it does support concurrent requests: It will spawn 1 goroutine per requests and yield control between goroutines while they are performing I/O.

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