aspnetcore: Memory Leak in new ASPNET 2.2 routing?

Describe the bug

I was editing some Razor Pages (the Project\Pages kind) then refreshing the changes in Chrome (Version 71.0.3578.98). My dev loop is tight, so I make a small edit then refresh the page, and the change is visible in Chrome.

Eventually, I noticed my edits were not making their way to the browser. On a few occasions, I noticed waiting a longer time delay before refreshing the browser sometimes helped the situation. Eventually, though, edits would no longer make their way to the browser.

Originally, I was using InProcess but decided to switch to OutOfProcess, rebooted PC, and the same problem occurred. Somewhere between 15 minutes to 1 hour of constantly editing Razor Pages in Visual Studio, I begin to notice my edits not showing up in the browser.

With out of OutOfProcess enabled, I noticed, a massive 9.7 GB memory usage in dotnet.exe

(later, trying to debug dotnet.exe, we’re up at 27GB)

dotnet.exe:

As dotnet.exe consumes memory, there appears to be a few threads that pop off coreclr_shutdown. Not much to discern, but worth noting.

Next, I attached a VS debugger to dotnet.exe, broke into the debugger and landed in Program.Main(). None of my user code was running. Continue & Pausing the debugger multiple times did show one thread standing out. Specifically, Thread 3952 playing around in the new ASPNET Core 22 routing code? Microsoft.AspNetCore.Routing.DecisionTree.

Specifically, Array.Copy, DecisionTree.Resize and Capacity.set seem to be popular destinations with Thread 3952. Thread 3952 is the only thread that appears to be active during this memory leak.

To Reproduce

Steps to reproduce the behavior:

1. Using this version of ASP.NET Core ‘2.2’
2. Edit somewhat complex Razor Pages for about 15 minutes to 1 hour in a tight dev loop.

Expected behavior

I should be able to make edits in Razor Pages and see my changes in the browser without having to restart IISExpress or kill dotnet.exe manually or experience a memory leak during the editing experience.

Additional context

Operating System

• Windows 7

IDE

• Visual Studio 15.9.4

C:\>dotnet --info
.NET Core SDK (reflecting any global.json):
 Version:   2.2.101
 Commit:    236713b0b7

Runtime Environment:
 OS Name:     Windows
 OS Version:  6.1.7601
 OS Platform: Windows
 RID:         win7-x64
 Base Path:   C:\Program Files\dotnet\sdk\2.2.101\

Host (useful for support):
  Version: 2.2.0
  Commit:  1249f08fed

.NET Core SDKs installed:
  1.0.0 [C:\Program Files\dotnet\sdk]
  1.0.1 [C:\Program Files\dotnet\sdk]
  1.0.2 [C:\Program Files\dotnet\sdk]
  1.0.3 [C:\Program Files\dotnet\sdk]
  1.0.4 [C:\Program Files\dotnet\sdk]
  1.1.0 [C:\Program Files\dotnet\sdk]
  2.0.0 [C:\Program Files\dotnet\sdk]
  2.0.3 [C:\Program Files\dotnet\sdk]
  2.1.4 [C:\Program Files\dotnet\sdk]
  2.1.101 [C:\Program Files\dotnet\sdk]
  2.1.103 [C:\Program Files\dotnet\sdk]
  2.1.104 [C:\Program Files\dotnet\sdk]
  2.1.200 [C:\Program Files\dotnet\sdk]
  2.1.201 [C:\Program Files\dotnet\sdk]
  2.1.202 [C:\Program Files\dotnet\sdk]
  2.1.300 [C:\Program Files\dotnet\sdk]
  2.1.302 [C:\Program Files\dotnet\sdk]
  2.1.401 [C:\Program Files\dotnet\sdk]
  2.1.402 [C:\Program Files\dotnet\sdk]
  2.1.403 [C:\Program Files\dotnet\sdk]
  2.1.500 [C:\Program Files\dotnet\sdk]
  2.1.502 [C:\Program Files\dotnet\sdk]
  2.2.100 [C:\Program Files\dotnet\sdk]
  2.2.101 [C:\Program Files\dotnet\sdk]

.NET Core runtimes installed:
  Microsoft.AspNetCore.All 2.1.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.3 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.4 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.5 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.6 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.2.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.App 2.1.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.3 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.4 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.5 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.6 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.2.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 1.0.4 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 1.0.5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 1.1.1 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 1.1.2 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.0.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.0.3 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.0.5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.0.6 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.0.7 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.0.9 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.2 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.3-servicing-26724-03 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.3 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.4 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.6 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.2.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]

To install additional .NET Core runtimes or SDKs:
  https://aka.ms/dotnet-download

Also, here is Process Monitor monitoring file access during the memory leak event:

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I will continue to do more testing to see if I can narrow down the issue. Thanks for your help in advance.

Thanks, Brian Chavez

🍫 🍪 🍭 Ronald Jenkees - Stay Crunchy