A Challenging Craft

Customer

Fabian

My day to day job is to help customersfixing software performance

People really struggle with performance

But most of them struggle with coding as well

That‘s me

If creating good software is a craft,performance should be one as well

Art

Some say:„creating software is art“

Art and software developmentneed creativity

Magic

Fixing performance isoften considered magic

Magic is something only you understand

you do in a hard tofollow fashion

Craft

Correctness in detail

Research and verification

Which way?

All types share Passion

Learning

Experience

Money

(in parts of the world)

Value == Money

We need a business casefor performance

What is the impact ofbad performance?

Typical (?) retailer

Amazon measured theimpact of 100ms delay

Sales dropped by 1%

In a year that would be245 Million USD

New?

Instable or slow softwaredelays time to market

Slow software is no longeraccepted by customers

Snail Mail

Insurances like to sendpaper via mail

Not meeting deadlines cancause Legal issues

Canceled contracts

Loss of money

Is A Craft

Performance

Engineering

Calculate Execution Time Code x = 5ms

Code y = 2*x = 10ms

Know code in advance

Waterfall approach

Proving the performance of softwareis more difficult than proving the correct function

Look closely

We prove functionalcorrectness with automatedtests

High coverage

Run examples and see if they are fast

How much load

breaks the system?

Done late in project

If done at all

No chance to fix anything

42cm are fast?

Avoid human errors

Require machine decidablefail / pass check

What is the measure?

Our Environment

Functionality is independentof the environment

Performance characteristicscan vary Unusable slow

Lightning fast

Developers

driving fast

Underpowered hardware

Loaded with toolsand stuff

Luckily not the productionenvironment

Crawling Production

More power

But also more load

How much faster isproduction than development?

Any estimation on how much better or worse theenvironments are is incorrect

Stop playing

Real performance testsneed real systems

Test in production

Clone productioninfrastructure

Tweets per second

Amount of data isunpredictable

Application usage isunpredictable

How thought of using Twitter for build notification?

Dev

Test Test1

Test Test2

Test Test3

Showing 3/3

Fabian Lange

Uwe Friedrichsen

Mirko Novakovic

Showing 3/6,434,867

Prod

Load Baselines

Syntethic load tests areunrealistic

No application has hundredsof users doing the sameprocedure again and again

Understanding real load is difficult

Live Systems are live

Real usage cannotbe generated

Real usage can becaptured & replayed

Be careful

App Monitor

Continous performance tests

Close to real setup

Observe production behavior

Fix issues fast

Another Movement

Conflicting interests Development: Change

Operations: Stability

Need to work together

Is A Challenge

Let users test?

Can‘t we do anything beforeproduction?

We want to deliver something,which works perfectly!

Missed Target

Optimizations might haveno impact

Micro-Optimizations aredangerous

Sonar

Soft Measure

Works good for code quality

Are there performance best practices?

Good Waterfalls

Yahoo Best Practices

Google Best Practices

Plenty of tools

Work well

Naive implementation looks fine

But is not multithreaded

This is threadsafe

But slow

This is correct

Correct synchronisation is hard

Check Log Level (Ugly)

Check Log Level (Nicer)

Static SimpleDateFormat is wrong

Working with Datesand Calendars isvery expensive!

Some people misuse it as loop

Results are unexpected behavior or slow execution

Indeed finds bugs

Analyzes Java Bytecode

Knows 58 Performance Bugs

Most are rather trivial

Verifies Java

Detecting deadlocksis difficult

Many thesis's on deadlockdetection

Few code

IBM

Support Assistant

Hidden Gem

Tries to cause Deadlocks

We need more and reliable Code Performance Metrics

Best Practices

Tools

Is A Challenging Craft

Q & A

Art flickr.com/photos/37202375@N03/3490107873

Magicflickr.com/photos/princes_milady/4238912548

Crossroadsflickr.com/photos/40481200@N06/4857965280

Envelopesflickr.com/photos/creatingmotherhood/3663914542

Testflickr.com/photos/cayusa/2159980025

Scalesflickr.com/photos/reinvented/309512320

Tape Measureflickr.com/photos/hippie/2466583497

World flickr.com/photos/heimdahlrecounts/4346082743

Toysflickr.com/photos/sbluerock/364123380

TPSflickr.com/photos/twitteroffice/5681263084

Bananasflickr.com/photos/design-dog/1249337589

Dartflickr.com/photos/malavoda/2369876508

YSlowdeveloper.yahoo.com/yslow

Pagespeedcode.google.com/speed/page-speed

Java Lockingen.wikipedia.org/wiki/Double-checked_locking

PHP Ternary Operatorfabien.potencier.org/article/48/the-php-ternary-operator-fast-or-not

JavaScript for .. Instackoverflow.com/questions/500504/javascript-for-in-with-arrays

Findbugsfindbugs.sourceforge.net

Jlintjlint.sourceforge.net

IBM Multicore SDKwww-01.ibm.com/support/docview.wss?uid=swg21456945