The document discusses the importance of performance in software development, focusing on measurement and optimization strategies. It offers practical advice on identifying bottlenecks, utilizing benchmarking, and understanding the impacts of garbage collection. Additionally, it highlights lessons learned from roslyn's performance, including avoiding boxing, minimizing LINQ usage, and implementing object pooling.

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

16. Stack Overflow Performance Lessons

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

20. 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

21. 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

22. 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);
}
}

23. 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

24. 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();
}
}

25. 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

26. 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;
}

27. Roslyn Performance Lessons Demo

28. Resources

29. Questions?
@matthewwarren
www.mattwarren.org