ASP.NET Web Api 2 / EF6首先调用初始化性能 [英] ASP.NET Web Api 2 / EF6 first call initialization performance
问题描述
我们API的第一次调用总是非常慢。例如，下面演示了第一次调用完成CPU使用情况和时间：
第一个电话可能需要30秒的时间才能使用100％的CPU。呼叫2和3需要200ms（应该）。在回收应用程序池之后，它将在第一次调用中执行相同的操作。
我已经阅读了有关IIS的热身，并完成了以下操作，但没有变化：
这里似乎她不只是在谈论初始加载，而是实际上首次使用一个上下文我会快速搜索Julie Lerman和Entity Framework的性能问题。在对我的Web API进行初始调用时，我注意到类似的缓慢。第一次之后的每个电话都明显更快。我个人并没有发现这太可怕了，所以我忽略它（现在）。然而，我确实发现它不会在调试模式下发生。对不起，如果您已经探索了这些选项，但希望这有所帮助。
The first call to our API is always extremely slow. For example, below demonstrates the CPU usage and time it takes for the first call to complete:
The first call can take up to 30 seconds and eats almost 100% CPU. Call 2 and 3 take 200ms (as they should). After recycling the application pool, it will do the same thing with the first call.
I've read a bit about IIS "warm-up" and done the following, but nothing has changed:
IIS 8 Application Initialization is installed:
I have the following set in IIS:
- Set Start Mode to AlwaysRunning:
- Set the Recycling Timeout to 0:
- Set the Idle Time-out to 0:
- Set Preload Enabled to true on the site:
I am actually setting these in code in RoleEntryPoint.OnStart().
using (var serverManager = new ServerManager())
{
serverManager.ApplicationPoolDefaults.ProcessModel.IdleTimeout = TimeSpan.Zero;
foreach (var application in serverManager.Sites.SelectMany(x => x.Applications))
{
application["preloadEnabled"] = true;
}
foreach (var applicationPool in serverManager.ApplicationPools)
{
applicationPool.AutoStart = true;
applicationPool["startMode"] = "AlwaysRunning";
applicationPool.ProcessModel.IdleTimeout = TimeSpan.Zero;
applicationPool.Recycling.PeriodicRestart.Time = TimeSpan.Zero;
}
serverManager.CommitChanges();
}
I am almost certain that Entity Framework could be the culprit:
We are generating models from around 100 tables in a EDMX model "designer".
We are generating precompiled views generated by EF Power Tools.
The following initialization is running in
Application_Start():using (var context = new MyContext()) { context.Database.Initialize(false); }
I don't have these "initialization" problems when debugging.
The following tech is being used:
- .NET 4.5.1
- ASP.NET Web Api 2
- Entity Framework 6.1.1
- IIS 8 (Azure Web Role)
- Unity 3.5
Can anyone provide me with any other ideas or suggestions?
Not sure if anyone has addressed this yet, but I've learned about some performance issues arising on the initial startup of Entity Framework. Julie Lerman discussed this in her Pluralsight course on Entity Framework, and is also alluded to in the following article excerpt from Microsoft:
One of the biggest drags on performance is the startup time involved with the first use of a context in an application process. You can do a lot to improve that startup time, though. Hopefully you’ve already learned these tricks from my own writing or other resources, such as the MSDN doc on performance considerations at bit.ly/3D6AiC.
A startup step that often hampers performance is the view generation of mapping views, where EF creates the relevant SQL to query against each of the entity sets in the model. These views get leveraged as your app runs so that for certain queries, EF doesn’t have to work out the SQL on the fly. View generation happens whether you created your model with the EF Designer or with Code First. You can pre-generate these views and compile them into the application to save time. http://msdn.microsoft.com/en-us/magazine/dn532202.aspx
Here it seems she's not just talking about the 'initial load' but the actual first use of a context. I'd to a quick search for Julie Lerman and Entity Framework performance issues. I noticed similar slowness when making the initial calls to my Web API. Every call after the first was significantly faster. I personally haven't found it to be too awful, so I'm ignoring it (for now). However I do find it interesting that it doesn't occur in debug mode. Sorry if you've already explored these options, but I hope this helps a little.
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