Why ASP Net Core 2.2 do not release memory?

Question

I\'m testing ASP Net Core 2.2 using default project made from:

Visual Studio > File > New > Project > ASP NET Core Web Application > Next > Create. Press IIS

Answer 1

I was struggling with the same issue. After a little research i found that .NET Core allocating new memory space if it can. It will be released if it is necessary, but this release is more resource demanding than the other releasing, because you have to use the GC this way:

GC.Collect(2, GCCollectionMode.Forced, true);
GC.WaitForPendingFinalizers();

My solution was to create a middleware:

using Microsoft.AspNetCore.Http;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;

namespace RegisterValidator
{
    public class GCMiddleware
    {
        private readonly RequestDelegate _next;

        public GCMiddleware(RequestDelegate next)
        {
            _next = next;
        }

        public async Task Invoke(HttpContext httpContext)
        {
            await _next(httpContext);
            GC.Collect(2, GCCollectionMode.Forced, true);
            GC.WaitForPendingFinalizers();
        }
    }
}

EDIT: this middleware will provide a GC.Collect after every call.

And register it in the Configure() method in Startup.cs:

    public void Configure(IApplicationBuilder app, IHostingEnvironment env, IServiceProvider service, ILoggerFactory loggerFactory)
    {

        app.UseMiddleware<GCMiddleware>();
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }
        else
        {
            app.UseHsts();
        }

        app.UseStaticFiles();
        //app.UseHttpsRedirection();
        app.UseMvcWithDefaultRoute();

        app.Run(async (context) =>
        {
            await context.Response.WriteAsync("\"No ");

        });
    }

Maybe there is another solution but I haven't found it yet. I hope it helps.

Edit: If you aren't sure that the memory usage is because there is a huge amount of allodated space of some other issue you can use dotMemory that will profile your memory usage with more detail than your Visual Studio.

Answer 2

ASP.NET Core can appear to use more memory than it should because it's configured to use Server GC by default (as opposed to Workstation GC). For a discussion of a similar concern see here. In theory, the application should be able to reduce its memory footprint when your server faces a memory pressure.

More on this topic in this MSDN doc and Github CoreCLR doc.

To see if it's indeed Server GC that causes the additional memory consumption, you can set GC strategy to workstation in your csproj file:

<PropertyGroup> 
    <ServerGarbageCollection>false</ServerGarbageCollection>
</PropertyGroup>