performance and how to measure it - progscon london 2016

Performance is a Feature!

Performance is a Feature!

Matt Warren

ca.com/apm

mattwarren.github.io

@matthewwarren

Front-end

Database & Caching

CLR/JVM

Mechanical Sympathy

Why does performance matter?

What do we need to measure?

How we can fix the issues?

Why?

Save money

Save power

Bad perf == broken

Lost customers

Half a second delay caused a 20% drop in traffic (Google)

Why?

http://engineroom.ft.com/2016/04/04/a-faster-ft-com/

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

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

Never give up your performance accidentally

Rico Mariani, Performance Architect @ Microsoft

What?

Averages

are bad

"most people have more than the averagenumber of legs"

- Hans Rosling

https://blogs.msdn.microsoft.com/bharry/2016/03/28/introducing-application-analytics/

Application Insights Analytics

When?

In production

You won't see ANY perf issues during unit tests

You won't see ALL perf issues in Development

How?

Measure, measure, measure

1. Identify bottlenecks

2. Verify the optimisation works

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.”

How?

https://github.com/opserver/Opserver

How?

Micro-benchmarks

How?

Profiling -> Micro-benchmarks

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>();}

http://github.com/PerfDotNet/BenchmarkDotNet

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)

BenchmarkDotNet

BenchmarkDotNet=v0.9.4.0





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 |

How?

Garbage Collection (GC)

Allocations are cheap, but cleaning up isn’t

Difficult to measure the impact of GC

https://samsaffron.com/archive/2011/10/28/in-managed-code-we-trust-our-recent-battles-with-the-net-garbage-collector

Stack Overflow Performance Lessons

Use static classes

Don’t be afraid to write your own tools

Dapper, Jil, MiniProfiler,

Intimately know your platform - CLR

Roslyn Performance Lessons 1

public class Logger{

public static void WriteLine(string s) { /*...*/ }}

public class Example{

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#fbid=

Roslyn Performance Lessons 1

public class Logger{

public static void WriteLine(string s) { /*...*/ }}

public class Example{

public void Log(int id, int size){

var s = string.Format("{0}:{1}", id.ToString(), size.ToString());

Logger.WriteLine(s);}

} AVOID BOXING Know what’s going on under the hood

Roslyn Performance Lessons 2class 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);}

}

Roslyn Performance Lessons 2class 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 LINQHigh level abstractions have a cost

BenchmarkDotNetBenchmarkDotNet=v0.9.4.0



Frequency=2630654 ticks, Resolution=380.1336 ns, Timer=TSC



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 |

Roslyn Performance Lessons 3public 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();

}}

Roslyn Performance Lessons 3public 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

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;

}

Reduce unnecessarily allocations

Questions?

@matthewwarren

mattwarren.github.io

performance and how to measure it - progscon london 2016

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