Fall creators update performance issues

Question

After the recent Windows 10 Update (Fall Creators Update) the performance of our .NET c# 4.0 application had decreased a lot. I think there are various issues and one of them is log4net (or disk IO).

Our application is very complex (various WCF applications and a ASPNET MVC 3.0 app) and in development there are a lot of log4net traces. Loading the first page in startup lasts 4 or 5 minutes and before the updates lasts a minute, If I deactivate log4net the performance.

I've done a test with two cloned virtual machines, logging after a regex operation, and the diferrences are significant.

The code:

    static void Main(string[] args)
    {
        Log.Info("Log4net1");

        DateTime start = DateTime.Now;

        for (int i = 0; i < 50; i++)
        {
            DoTheThing();
        }


        TimeSpan elapsedTime = DateTime.Now - start;
        Log.DebugFormat("TOTAL Elapsed time: {0}", elapsedTime.TotalMilliseconds);
        Console.ReadKey();
    }

    private static void DoTheThing()
    {
        DateTime start = DateTime.Now;
        Regex.Replace(TEXT, " nec ", m =>
        {
            return " (word nec) ";
        });
        TimeSpan elapsedTime = DateTime.Now - start;
        Log.DebugFormat("Elapsed time: {0}", elapsedTime.TotalMilliseconds);
    }

I've done tests with log4net 1.2.1 and 2.0.8:

average beforeUpdate -> TOTAL Elapsed time: 600ms

average afterUpdate -> TOTAL Elapsed time: 1000ms

It's a very important issue for us, and I haven't found any info on the net.

-- UPDATE --

I've found another (unanswered) thread on stackoverflow: log4net became very slow with caller location information after Windows 10 Fall Creators Update (1709)

I've ran a disk benchmark on both environments and there's no significant differences on read/write rates. I've tested the application disabling completely log4net (log4net threshold="OFF") and now the timings are very similar, so, as @DalmTo comments, there a lot of possibilities that it would be due to log4net, I'll try to put an issue there, although there is already a related microsoft issue: https://connect.microsoft.com/VisualStudio/feedback/details/3143189/after-installing-windows-10-1709-update-creating-a-stacktrace-class-has-become-a-magnitude-slower

Answer 1

You could be hit by this issue:

Starting in October 2017, after you upgrade to Windows 10 Version 1709 or .NET Framework 4.7.1, you notice a significant decrease in performance when you run .NET Framework applications that use the System.Diagnostics.StackFrame class.

Applications typically rely on StackFrame when they throw .NET exceptions. If this occurs at a high rate (more than 10 incidents per second), applications can slow down significantly (tenfold) and run noticeably slower than before.

https://support.microsoft.com/en-us/help/4057154/performance-of-system-diagnostics-stackframe-degrades-in-windows-10-17

The .NET Framework 4.7.1 added support for detecting and parsing the Portable PDB file format to show file and line number information in stack traces. As part of this change, each function in a stack trace has its defining module checked to determine if that module uses the Portable PDB format.

Due to some differences in the internal caching policy, the runtime spends far more time searching for Portable PDBs than previous .NET Framework versions spent searching for classic Windows PDBs. This causes formatted stack traces to be produced more slowly than before.

https://github.com/Microsoft/dotnet/blob/master/releases/net471/KnownIssues/517815-BCL%20Applications%20making%20heavy%20use%20of%20System.Diagnostics.StackTrace%20might%20run%20more%20slowly%20on%20.NET%204.7.1.md

Installing the latest .NET 4.7.1 Reliability Update (KB4054856) should resolve this.

• Windows 10 Fall Creators needs KB4058258 - https://support.microsoft.com/en-us/help/4058258

The following fixes are included: Applications making heavy use of System.Diagnostics.StackTrace or Exception.StackTrace might run more slowly on the .NET Framework 4.7.1.

https://blogs.msdn.microsoft.com/dotnet/2018/01/09/net-framework-4-7-1-is-available-on-windows-update-wsus-and-mu-catalog/