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Performance is a feature! - London .NET User Group

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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!

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Performance is a feature! - London .NET User Group

  1. 1. Performance is a Feature!
  2. 2. Performance is a Feature! Matt Warren ca.com/apm mattwarren.github.io @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 Peteroski
  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. Never give up your performance accidentally Rico Mariani, Performance Architect @ Microsoft
  9. 9. What? Averages are bad
  10. 10. "most people have more than the average number of legs" - Hans Rosling
  11. 11. https://blogs.msdn.microsoft.com/bharry/2016/03/28/introducing-application-analytics/ Application Insights Analytics
  12. 12. When? In production You won't see ANY perf issues during unit tests You won't see ALL perf issues in Development
  13. 13. How? Measure, measure, measure 1. Identify bottlenecks 2. Verify the optimisation works
  14. 14. 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.”
  15. 15. How? https://github.com/opserver/Opserver
  16. 16. How? https://github.com/opserver/Opserver
  17. 17. How? Micro-benchmarks
  18. 18. How? Profiling -> Micro-benchmarks
  19. 19. http://www.hanselman.com/blog/BenchmarkingNETCode.aspx
  20. 20. 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>(); }
  21. 21. 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)
  22. 22. 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 |
  23. 23. 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 |
  24. 24. [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(); }
  25. 25. How? Garbage Collection (GC) Allocations are cheap, but cleaning up isn’t Difficult to measure the impact of GC
  26. 26. https://samsaffron.com/archive/2011/10/28/in-managed-code-we-trust-our- recent-battles-with-the-net-garbage-collector
  27. 27. Stack Overflow Performance Lessons Use static classes Don’t be afraid to write your own tools Dapper, Jil, MiniProfiler, Intimately know your platform - CLR
  28. 28. 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
  29. 29. 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); } } AVOID BOXING
  30. 30. 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); } }
  31. 31. 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
  32. 32. 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 |
  33. 33. 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(); } }
  34. 34. 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
  35. 35. 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; }
  36. 36. Questions? @matthewwarren mattwarren.github.io https://confocal.io/ Code: matt

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