Google App Engine Node.js本地开发 [英] Google app engine nodejs local development

问题描述

是否有一种方法可以在本地运行我的nodejs应用程序，以便我可以模拟在生产App Engine中运行的应用程序而无需进行部署?由于某些原因，与本地主机相比，我的应用在Google App Engine中的行为有所不同.

每当我进行更改以查看是否存在错误时，我都厌倦了将应用程序部署到Google App Engine的过程.

解决方案

在您的本地系统和真实的GAE基础架构上，您将永远不会完全获得相同的行为.一次是因为您运行的基础架构不同:操作系统，硬件和网络性能/功能，您的应用可能正在使用的实际与SDK模拟的Google API和服务的性能/功能，时间安排等.

一些示例(它们来自标准的env GAE，是的，但是从根本上讲是相同的想法):

• FetchOptions withLimit()不会减少查询执行时间(Google App Engine)
• 数据存储区提取VS fetch(keys_only = True)然后get_multi
• Ndb的一致性强且写入频繁

您应该调查这些差异-非常欢迎您在SO上就其中的每个问题提出疑问.

通常，您会发现两类差异:

• 预期的性能差异，但它们可能会发现代码中的实际问题:竞争条件，错误的时序假设等

• 功能差异-查找要在GAE而非本地进行测试的常规区域.

  例如，我(艰难地)了解到，SDK数据存储区模拟器无法模拟真实数据存储区中的竞争逻辑-虽然我的应用在本地运行良好，但在GAE上，由于竞争，它的爬坡非常糟糕，我不得不重新编写逻辑的一个很好的部分来解决它.请参见 Google App Engine中的竞争问题

Is there a way to run my nodejs application locally so that I can simulate my application running in production App Engine without deploying it? For some reason my app behaves differently in the Google App Engine compared to my localhost.

I am getting tired of deploying my application to Google App Engine every time I make a change just to see if there's a bug.

解决方案

You'll never get exactly the same behaviour on your local system and on the real GAE infrastructure. For once simply because the infrastructure on which you're running is different: OS, hardware and network performance/capabilities, performance/capabilities of the actual vs SDK-simulated google APIs and services your app may be using, timing, etc.

A few examples (they're from the standard env GAE, it's true, but it's fundamentally the same idea):

• FetchOptions withLimit() does not reduce query execution time (Google App Engine)
• Datastore fetch VS fetch(keys_only=True) then get_multi
• Why does Google Cloud SQL (using JDBC) take longer to insert records from Google App Engine than from my personal computer?
• Ndb strong consistency and frequent writes

You should investigate the differences - you're more than welcome to ask questions about each one of them right here, on SO.

In general you'll find the differences falling in 2 categories:

• plain performance differences, expected, but they may uncover actual problems in your code: race conditions, wrong timing assumptions, etc

• functional differences - to find general areas where you want to perform testing on GAE rather than locally.

  For example I learned (the hard way) that the SDK datastore emulator doesn't emulate the contention logic from the real datastore - while locally my app was running fine, on GAE it was crawling miserably due to contention, I had to re-write a good portion of the logic to address it. See Contention problems in Google App Engine

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