.Net Core 2.1.6+EF Core 2.2.0 , memory leak happened

[LMing123]

I use a function in linq expression, then GC can't collect memory.

Steps to reproduce

    public class GuessWhatController : ControllerBase
    {
        protected GuessWhatContext context;
         public ActionResult MatchList()
        {
            var matchs = context.Matches.Include(y => y.MatchBanner).OrderByDescending(x=>x.EndTime);
            var recommends = context.Recommends.Include(y => y.Match);
            return new JsonResult(matchs.Select(x => new
            {
                id = x.ID,
                x.Title,
                startTime = x.StartTime.ToString("yyyy-MM-dd"),
                endTime = x.EndTime.ToString("yyyy-MM-dd"),
                x.NeedVIP,
                x.MatchDetail,
                x.Price,
                banner =x.MatchBanner.URL==null?GetImageUrl(x.MatchBanner.ID): x.MatchBanner.URL,  //this line have a problem
            }));
        }
        public string GetImageUrl(int? imageID)
        {
            return $"api/GuessWhat/ImageShow/{imageID}";
        }
    }

It cause that memory keep increasing and CG can't collect, but i change code

 banner =x.MatchBanner.URL==null?GetImageUrl(x.MatchBanner.ID): x.MatchBanner.URL,

to this

 banner =x.MatchBanner.URL==null? $"api/GuessWhat/ImageShow/{x.MatchBanner.ID}" : x.MatchBanner.URL,  

the problem is resolved.

Further technical details

EF Core version: 2.2
Database Provider: Pomelo.EntityFrameworkCore.MySql
Operating system: Windows 10 1809 17763.168
IDE: Visual Studio 2017 15.9.3

[crucialize]

Hey, I've also found a memory leak bug just now!

[smitpatel]

Duplicate of #13048

[smitpatel]

The issue here is, in order to perform client eval requested by user, we capture the closure. But closure also contains the DbContext hence memory is leaked. Easy work-around for now would be to use static method which wouldn't capture the instance of repository