ApiController: memory leak when returning large string arrays #55179
Description
Is there an existing issue for this?
- I have searched the existing issues
Describe the bug
When returning a large string in my ApiController, the process memory goes up. But even after the garbage collector was triggered (manually or automatically), the memory doesn't fall back like you expect.
A small code example is listed below. The full minimal project is linked further down.
[HttpGet("memory")]
[OutputCache(Duration = 0, NoStore = true)]
public IEnumerable<string> Memory()
{
List<string> list = new();
for (var i = 0; i < 1_000_000; i++)
{
list.Add(i.ToString());
}
return list;
}
Expected Behavior
I expect the memory to fall back. When I also create a list in a small console application, the memory falls back like expected. This console project is listed below and in the reproduce repo I linked.
while (true)
{
GC.Collect();
GC.WaitForPendingFinalizers();
Console.ReadLine();
var list = GetList();
Console.WriteLine(list.Count);
}
List<string> GetList()
{
List<string> list = new();
for (int i = 0; i < 1_000_000; i++)
{
list.Add(i.ToString());
}
return list;
}
Steps To Reproduce
I created a minimalistic project in the following repository: https://github.com/Paultje52/aspnet-string-array-memory-issue
This repository consists of two project: WebApplication with the issue in an ApiController and ConsoleApp with the expected behaviour in a console application.
Go to the page http://localhost:5100 to get the list and trigger the memory issue. After making that request multiple times, go to http://localhost:5100/collect to manually trigger the garbage collector.
Exceptions (if any)
No response
.NET Version
8.0.202
Anything else?
ASP.NET Core: 8.0.3
IDE: Visual Studio 17.9.5
Dotnet info
.NET SDK:
Version: 8.0.202
Commit: 25674bb2f4
Workload version: 8.0.200-manifests.8cf8de6d
Runtime Environment:
OS Name: Windows
OS Version: 10.0.22631
OS Platform: Windows
RID: win-x64
Base Path: C:\Program Files\dotnet\sdk\8.0.202\
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Host:
Version: 8.0.3
Architecture: x64
Commit: 9f4b1f5d66
.NET SDKs installed:
8.0.202 [C:\Program Files\dotnet\sdk]
.NET runtimes installed:
Microsoft.AspNetCore.App 6.0.28 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 7.0.17 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 8.0.3 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.NETCore.App 6.0.28 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 7.0.17 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 8.0.3 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.WindowsDesktop.App 6.0.28 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 7.0.17 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 8.0.3 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Other architectures found:
x86 [C:\Program Files (x86)\dotnet]
registered at [HKLM\SOFTWARE\dotnet\Setup\InstalledVersions\x86\InstallLocation]
Environment variables:
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global.json file:
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