Performance and how to measure it - ProgSCon London 2016

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

"most people have
more than the average
number 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?
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
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

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

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);
}
}

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
High level abstractions have a cost

BenchmarkDotNet
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 |

{
// 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();
}
}

{
// 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

[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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