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Performance is a Feature! at DDD 11

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Performance is a Feature! at DDD 11

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Starting with the premise that "Performance is a Feature", this session will look at how to measure, what to measure and how get the best performance from your .NET code.

We will look at real-world examples from the Roslyn code-base and StackOverflow (the product), including how the .NET Garbage Collector needs to be tamed!

Starting with the premise that "Performance is a Feature", this session will look at how to measure, what to measure and how get the best performance from your .NET code.

We will look at real-world examples from the Roslyn code-base and StackOverflow (the product), including how the .NET Garbage Collector needs to be tamed!

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Performance is a Feature! at DDD 11

  1. 1. Performance is a Feature!
  2. 2. Performance is a Feature! Matt Warren ca.com/apm www.mattwarren.org @matthewwarren
  3. 3. Front-end Database & Caching .NET CLR Mechanical Sympathy
  4. 4. Why does performance matter? What do we need to measure? How we can fix the issues?
  5. 5. Why? Save money Save power Bad perf == broken Lost customers Half a second delay caused a 20% drop in traffic (Google)
  6. 6. Why? “The most amazing achievement of the computer software industry is its continuing cancellation of the steady and staggering gains made by the computer hardware industry.” - Henry Petroski
  7. 7. Why? “We should forget about small efficiencies, say about 97% of the time: premature optimization is the root of all evil. Yet we should not pass up our opportunities in that critical 3%.“ - Donald Knuth
  8. 8. Why? “We should forget about small efficiencies, say about 97% of the time: premature optimization is the root of all evil. Yet we should not pass up our opportunities in that critical 3%.“ - Donald Knuth
  9. 9. Never give up your performance accidentally Rico Mariani, Performance Architect @ Microsoft
  10. 10. What? Averages are bad
  11. 11. "most people have more than the average number of legs" - Hans Rosling
  12. 12. https://www.ted.com/talks/hans_rosling_shows_the_best_stats_you_ve_ever_seen
  13. 13. https://blogs.msdn.microsoft.com/bharry/2016/03/28/introducing-application-analytics/ Application Insights Analytics
  14. 14. When? In production You won't see ANY perf issues during unit tests You won't see ALL perf issues in Development
  15. 15. How? Measure, measure, measure 1. Identify bottlenecks 2. Verify the optimisation works
  16. 16. How? “The simple act of putting a render time in the upper right hand corner of every page we serve forced us to fix all our performance regressions and omissions.”
  17. 17. How? https://github.com/opserver/Opserver
  18. 18. How? https://github.com/opserver/Opserver
  19. 19. How? Micro-benchmarks
  20. 20. How? Profiling -> Micro-benchmarks
  21. 21. http://www.hanselman.com/blog/BenchmarkingNETCode.aspx
  22. 22. using BenchmarkDotNet.Attributes; using BenchmarkDotNet.Running; static Uri @object = new Uri("http://google.com/search"); [Benchmark(Baseline = true)] public string RegularPropertyCall() { return @object.Host; } [Benchmark] public object Reflection() { Type @class = @object.GetType(); PropertyInfo property = @class.GetProperty(propertyName, bindingFlags); return property.GetValue(@object); } static void Main(string[] args) { var summary = BenchmarkRunner.Run<Program>(); }
  23. 23. Compared to one second • Millisecond – ms –thousandth (0.001 or 1/1000) • Microsecond - μs –millionth (0.000001 or 1/1,000,000) • Nanosecond - ns –billionth (0.000000001 or 1/1,000,000,000)
  24. 24. BenchmarkDotNet BenchmarkDotNet=v0.9.4.0 OS=Microsoft Windows NT 6.1.7601 Service Pack 1 Processor=Intel(R) Core(TM) i7-4800MQ CPU @ 2.70GHz, ProcessorCount=8 HostCLR=MS.NET 4.0.30319.42000, Arch=32-bit RELEASE JitModules=clrjit-v4.6.100.0 Type=Program Mode=Throughput Method | Median | StdDev | Scaled | --------------------- |------------ |----------- |------- | RegularPropertyCall | Reflection |
  25. 25. BenchmarkDotNet BenchmarkDotNet=v0.9.4.0 OS=Microsoft Windows NT 6.1.7601 Service Pack 1 Processor=Intel(R) Core(TM) i7-4800MQ CPU @ 2.70GHz, ProcessorCount=8 HostCLR=MS.NET 4.0.30319.42000, Arch=32-bit RELEASE JitModules=clrjit-v4.6.100.0 Type=Program Mode=Throughput Method | Median | StdDev | Scaled | --------------------- |------------ |----------- |------- | RegularPropertyCall | 13.4053 ns | 1.5826 ns | 1.00 | Reflection | 232.7240 ns | 32.0018 ns | 17.36 |
  26. 26. [Params(1, 2, 3, 4, 5, 10, 100, 1000)] public int Loops; [Benchmark] public string StringConcat() { string result = string.Empty; for (int i = 0; i < Loops; ++i) result = string.Concat(result, i.ToString()); return result; } [Benchmark] public string StringBuilder() { StringBuilder sb = new StringBuilder(string.Empty); for (int i = 0; i < Loops; ++i) sb.Append(i.ToString()); return sb.ToString(); } https://github.com/dotnet/roslyn/issues/5388
  27. 27. How? Garbage Collection (GC) Allocations are cheap, but cleaning up isn’t Difficult to measure the impact of GC
  28. 28. https://samsaffron.com/archive/2011/10/28/in-managed-code-we-trust-our- recent-battles-with-the-net-garbage-collector
  29. 29. Stack Overflow Performance Lessons Use static classes Don’t be afraid to write your own tools Dapper, Jil, MiniProfiler, Intimately know your platform - CLR
  30. 30. Roslyn Performance Lessons 1 public class Logger { public static void WriteLine(string s) { /*...*/ } } public class Logger { public void Log(int id, int size) { var s = string.Format("{0}:{1}", id, size); Logger.WriteLine(s); } } Essential Truths Everyone Should Know about Performance in a Large Managed Codebase http://channel9.msdn.com/Events/TechEd/NorthAmerica/2013/DEV-B333
  31. 31. Roslyn Performance Lessons 1 public class Logger { public static void WriteLine(string s) { /*...*/ } } public class BoxingExample { public void Log(int id, int size) { var s = string.Format("{0}:{1}", id.ToString(), size.ToString()); Logger.WriteLine(s); } } https://github.com/dotnet/roslyn/pull/415 AVOID BOXING
  32. 32. Roslyn Performance Lessons 2 class Symbol { public string Name { get; private set; } /*...*/ } class Compiler { private List<Symbol> symbols; public Symbol FindMatchingSymbol(string name) { return symbols.FirstOrDefault(s => s.Name == name); } }
  33. 33. Roslyn Performance Lessons 2 class Symbol { public string Name { get; private set; } /*...*/ } class Compiler { private List<Symbol> symbols; public Symbol FindMatchingSymbol(string name) { foreach (Symbol s in symbols) { if (s.Name == name) return s; } return null; } } DON’T USE LINQ
  34. 34. BenchmarkDotNet BenchmarkDotNet=v0.9.4.0 OS=Microsoft Windows NT 6.1.7601 Service Pack 1 Processor=Intel(R) Core(TM) i7-4800MQ CPU @ 2.70GHz, ProcessorCount=8 Frequency=2630654 ticks, Resolution=380.1336 ns, Timer=TSC HostCLR=MS.NET 4.0.30319.42000, Arch=32-bit RELEASE JitModules=clrjit-v4.6.100.0 Type=Program Mode=Throughput Runtime=Clr Method | Median | StdDev | Gen 0 | Bytes Allocated/Op | ---------- |----------- |---------- |------- |------------------- | Iterative | 39.0957 ns | 0.2150 ns | - | 0.00 | LINQ | 53.2441 ns | 0.5385 ns | 701.50 | 23.21 |
  35. 35. Roslyn Performance Lessons 3 public class Example { // Constructs a name like "Foo<T1, T2, T3>" public string GenerateFullTypeName(string name, int arity) { StringBuilder sb = new StringBuilder(); sb.Append(name); if (arity != 0) { sb.Append("<"); for (int i = 1; i < arity; i++) { sb.Append('T'); sb.Append(i.ToString()); } sb.Append('T'); sb.Append(arity.ToString()); } return sb.ToString(); } }
  36. 36. Roslyn Performance Lessons 3 public class Example { // Constructs a name like "Foo<T1, T2, T3>" public string GenerateFullTypeName(string name, int arity) { StringBuilder sb = new AcquireBuilder(); sb.Append(name); if (arity != 0) { sb.Append("<"); for (int i = 1; i < arity; i++) { sb.Append('T'); sb.Append(i.ToString()); } sb.Append('T'); sb.Append(arity.ToString()); } return GetStringAndReleaseBuilder(sb); } } OBJECT POOLING
  37. 37. Roslyn Performance Lessons 3 [ThreadStatic] private static StringBuilder cachedStringBuilder; private static StringBuilder AcquireBuilder() { StringBuilder result = cachedStringBuilder; if (result == null) { return new StringBuilder(); } result.Clear(); cachedStringBuilder = null; return result; } private static string GetStringAndReleaseBuilder(StringBuilder sb) { string result = sb.ToString(); cachedStringBuilder = sb; return result; }
  38. 38. Questions? www.oz-code.com @matthewwarren www.mattwarren.org jetbrains.com/dotTrace jetbrains.com/dotMemory

Editor's Notes

  • Who has:      - any perf requirements     - perf requirements with numbers!     - any perf tests     - perf test that are run continuously
  • Who has:      - any perf requirements     - perf requirements with numbers!     - any perf tests     - perf test that are run continuously
  • Front-end
    - YSlow, Google PageSpeed, CDN & caching   
    - "High Performance Web Sites" by Steve Sounder
    Database & caching
    - Learn to use SQL Profiler 
    - Redis or similar
    - MiniProfiler
    .NET (server-side) <- This is what we are looking at
    Mechanical Sympathy
    - Anything by Martin Thompson
    - Disruptor and Disruptor.NET 
    - CPU caches (L1, L2, etc)
    - memory access patterns
  • Save money when running in the cloud (Zeeshan anecdote)   - Scale-up rather than just scale-out - Save power on mobile devices (also bad perf more obvious on constrained device) - To users bad performance looks like you're website isn't working!   - PerfBytes podcast, "News Of The Damned", a.k.a "which UK ticketing site has crashed this week"! - Bad performance might be losing you customers, before you even got them!!
    - Even internal L.O.B apps   - What could Dave in accounting do with an extra 50 minutes per week (10 min per/day)   - Maybe the really slow accounting app is the reason for him quitting and going to work for your main competitor!! 
  • Henry Petroski (February 6, 1942) is an American engineer specializing in failure analysis. A professor both of civil engineering and history at Duke University, he is also a prolific author.

    To Engineer Is Human: The Role of Failure in Successful Design
  • To know the critical 3%, we have to measure,
    Except Donal Knuth, who never write slow code and
    if he did, he would know which bit was slow!
  • To know the critical 3%, we have to measure,
    Except Donal Knuth, who never write slow code and
    if he did, he would know which bit was slow!
  • Thanks him for making Visual Studio faster
    He helped fix it after adding WPF made it SLOW!!!!
  • Should be roughly 10-15 mins in by now, if not hurry up!!!!
  • Normal distribution
    Things like height, weight, DOESN’T apply to everything!!
  • Average is just less than 2, i.e. 1.995 or something like that
    But > 99% of people in the UK have 2 legs (more than the average)
  • This is a histogram,
    Real-world example
    Web page response times
    Why are there 2 groups of histograms bar?
    - fast = cached data
    - slow = hitting the database
  • Unit tests are meant to be fast, and they only test 1 thing

    In dev you don’t always have a full set of data
    You don’t test for long periods of time
    Smaller setup

    Michelle Bustamante talk about logging, don’t just need to measure things,
    Need to log the data AND be able to get at it!!
  • You’ll probably guess wrong!!

    Consider adding performance unit tests,
    Noda-Time does this, can graph performance over time, see if it’s regressed!!
  • MiniProfiler

    Turn this on in Development and if possible in Production

    Glimpse is an alternative
  • Runs on .NET,
    Puts everything in 1 place, Web Server & Database
    Summary metrics up front
    Can drill-down into detailed metrics, including executed SQL, page load times, etc
  • Make sure you are really measuring what you think you are measuring!!
  • Make sure you are really measuring what you think you are measuring!!
  • Nbench
    Xunit Performance
  • https://github.com/dotnet/roslyn/issues/5388
    Implement string concatenation in loops via manipulating a StringBuilder instead of emitting String.Concat()

    WON’T be implemented by the compiler
  • Both StackOverflow and Roslyn affected by this!!!!!

    In the .NET Framework 4.5, there is background server garbage collection (before .NET 4.5 was Workstation only)

    So until .NET 4.5, Server GC was STOP-THE-WORLD
  • Process Explorer
    From Sysinternals
  • PerfView is a stand-alone utility, to help you debug CPU and memory problems
    Light-weight and non-intrusive, can be used to on production apps with minimal impact
    Uses ETW (Event Tracing for Windows), designed to be v. fast!!!!
  • They were able to graph these results & equate them to Garbage Collector pauses!!!
    They had good logging and measurements in place,
  • They measured and found that all of these were on the HOT PATH
  • https://github.com/dotnet/roslyn/pull/415
    Avoid unnecessary boxing with String.Concat


    Able to implement this optimization for types which are immutable, pure, and not affected by other code. Notably:
    - bool
    - char (and this was one of the motivating types for this optimization)
    - IntPtr
    - UIntPtr

    Due to side-effects of calling ToString() implementations that rely on the current culture (i.e. it culture can be changed mid-way through and you’ll see different behaviour)
  • Repeat questions back to the audience!!!!!
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