1.
Performance is a Feature!

2.
Why does performance matter?
What do we need to measure?
How we can fix the issues?

3.
Front-end
Database & Caching
.NET CLR
Mechanical
Sympathy

4.
How?
Measure, measure, measure
1. Identify bottlenecks
2. Know the optimisation works

5.
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.”

6.
How?
https://github.com/opserver/Opserver

7.
How?
https://github.com/opserver/Opserver

8.
How?
The Art of Benchmarking
Profiling -> Micro-benchmarks

9.
static void Profile(int iterations, Action action)
{
action(); // warm up
GC.Collect(); // clean up
var watch = new Stopwatch();
watch.Start();
for (int i = 0; i < iterations; i++)
{
action();
}
watch.Stop();
Console.WriteLine("Time Elapsed {0} ms",
watch.ElapsedMilliseconds);
}
http://stackoverflow.com/questions/1047218/benchmarking-small-
code-samples-in-c-can-this-implementation-be-improved

10.
private static T Result;
static void Profile<T>(int iterations, Func<T> func)
{
func(); // warm up
GC.Collect(); // clean up
var watch = new Stopwatch();
watch.Start();
for (int i = 0; i < iterations; i++)
{
Result = func();
}
watch.Stop();
Console.WriteLine("Time Elapsed {0} ms",
watch.ElapsedMilliseconds);
}

11.
BenchmarkDotNet

12.
BenchmarkDotNet Demo

13.
How?
Garbage Collection (GC)
Allocations are cheap, but cleaning up isn’t
Difficult to measure the impact of GC
http://www.slideshare.net/benemmett/net-memory-management-ndc-london
https://vimeo.com/113632451

14.
Stack Overflow Performance Lessons

15.
Stack Overflow Performance Lessons
Use static classes
Don’t be afraid to write your own tools
Dapper, Jil, MiniProfiler,
Intimately know your platform - CLR

16.
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, size);
Logger.WriteLine(s);
}
}
Essential Truths Everyone Should Know about Performance in a Large Managed Codebase

17.
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

18.
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);
}
}

19.
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

20.
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();
}
}

21.
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

22.
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;
}

23.
Roslyn Performance Lessons Demo

24.
Resources

25.
Questions?
@matthewwarren
www.mattwarren.org