Joy Inc is really Joyful

I heard closing keynote talk by Richard-Sheridan at agile singapore conference where he shared how he build joyful company.

Richard has published book Joy, Inc.: How We Built a Workplace People Love to share his experience of building amazing organization.

I got copy of book few days back and started reading it, it is very difficult to put it down once you pick it up.
I have read few chapters in last 2 days and want to share few things that i liked .

Book starts with "Let's try something new, let't run an experiment", this is very good approach to plant seed for change.

Tangible Joy
Book define tangible joy as "delivering a product or service to world that's so enjoyed , in fact , that people stop you on the street and say,"really, you did that ? i love it"

By reading this i realized that how crappy product i have build :-(

Stupid Users
It has section on stupid user and context it that software industry think users are stupid and they need Dummies book to help them successfully use our beautifully designed technology because they are dump and don't understand our master piece.

Joy will lift you and your team
He gives reason why Wright brothers were able to fly and Samuel Pierpont Langley was not

Langley was trying to build an airplan. The Wright brothers wanted to fly.

This is so much applicable to our industry, we are so much after bleeding edge technology that we forget the real problem that is supposed to be solved by technology

Lots of experiment
This book is full of experiment he did to build Joy Inc.

Pair Programming
Everybody knows benefit of pairing but still many organization are reluctant to try

Wide Open space
Wide open space with no office,cubes is very good for collaborative work, but organization has Cube culture and with every promotion individual moves away from team and get locked in private office.

Rewards System
With culture change rewards system should also change , but most of the organization never change rewards system.
I think this is one of the main topic of book, few things mention in book are.

 Now you have fair idea about what rewards system should look like

Risk of staying same
This was eye opening "The risk of staying the same had been far greater than the risk of change"

Big-Dog Discussion
Big dogs in organization are special people and by looking at them voice echos in your ear
"You don't matter as much as I do"
@menlo big decision are not made in close door conference room so that people don't feel that they are not important.

Tower of knowledge
Book as very nice section about "Mr Dave" - person on team who has vast technical knowledge that no one else have.
This is such a common problem and most of the organization falls in this trap and it is very common in Banks.
Dave is bottleneck of entire organization or department and he can't go on vacation!
Pair programming is the recommended solution for Dave and organization


Books has lots of practical advise, i highly recommend this book.

Some talks/podcast by Richard
A CEO’S JOURNEY TO CREATING A CULTURE WHERE PEOPLE CAN THRIVE
Joy, Inc. | Rich Sheridan

Integer Encoding Magic

Question was asked to me on serializable/externalizable and why externalizable is fast , my answer was not convincing , so i spend some time on google to get more details and web has tons of information on it.

I thought of spending some time on open source serialization framework to check what type of optimization are done to reduce size.

One of the technique for integer type is use encoding, this technique is based on very simple rule.

Integer is of 4 Byte and if value is small then we don't have to use 4 byte to store it, so that way for small input values this technique can reduce size by great extent.

Some bitwise magic is required to achieve this.
I did quick compare of Raw vs Encoding and results were very good. In this test i write 1 Million integer values starting from 0 .

Without encoding it took 4019 KB for 1 Million and with byte encoding it took 2991 KB, encoding gives around 25% gain for this sample test.

Integer Encoding
Code snippet for integer encoding, it is taken from Apache Avro


Conclusion 
 Integer encoding technique gives good gain for size , but it adds overhead on write/read side, so it should be used by knowing the  side effect , such approach is very good for serialization framework because you want to reduce size of data that is sent over wire or written to some persistent store.

Coded used for this blog is available @ github

Experiment with String Split

Splitting string based on some token is very common operation in application, in this blog i will share some options that are mostly used and types of overhead involved in it.

String.split
This is the most common approach and it looks harmless unless you look at the code!
First it creates ArrayList for storing values and then this arraylist is converted to String array

This function produces too much of garbage and it provides only one way to extract values.

String Tokenizer 
This is much better than String.split because it does not need intermediate buffer like ArrayList/String Array to hold the values, but it creates String objects for each token which adds to garbage.

One of the good thing about StringTokenizer is that it does not force caller to use fixed data structure , so caller is free to decide on what to do with values, it is just like Streaming operation.

String.split vs StringTokenizer
Lets look at some performance numbers. In this test i take below sample string

String[] values = {
        "this,is,simple,test",

        "lets,see,how,it,works",

        "this,is,very,simple,test"};

Each line is split 10 million times

So definitely StringTokenizer is winner in this case and it is because it produces less garbage as compared to String.split but it still produces string objects.

It is possible to avoid creating those String object also by using Recycle Charsequence which is just like String but gives lots of flexibility.

Lets look at another implementation using recycle charsequence approach.


It is very simple technique to avoid intermediate string object, lets look at performance number using this approach.

Recycle charSequence shines in this test, it is around 3X times faster than String.split an 2X times faster than StringTokenizer.

Code available @ github

Java8 Parallel Streams

Recently found great article on when to use Parallel Stream by Doug lea and team. In this blog i will share some performance result of different data structure.

Splittable data structure
This is one of the most important factor that needs to be consider. All the parallel stream operation are executed using default fork join pool and fork join pool uses Divide and conquer algorithms to split stream in small chunks and apply function on small chunks, so splitting is important factor and if splitting is going to take more time then all computation is going to choke!

Types of datastructure

-Array
Array based data structure are most efficient data structure from splitting perspective because each element can be randomly accessed , so splitting is very quick operation.
Some of the example of array based collections are ArrayList & open addressing based Set/Map.

-Tree
Balanced tree based collection like TreeMap or ConcurrentHashMap. It is easy to chop the collection into 2 parts, but if tree is not balanced then splitting will be not that efficient because task load will be not equal for each thread.
Another thing to consider is that memory access pattern for tree based data structure is random , so there will be memory latency cost when elements are accessed.

-LinkedList
This type of data structure gives worst splitting performance because each element must be visited to split it. Some of the samples from JDK are LinkedList,Queues

- Others
This for all others type of datastructure for eg I/O based , BufferedReader.lines which returns stream but splitting operation is very expensive.

Some performance numbers
All performance tuning guess must be backed by experiment, so lets have look at some numbers.

Some code snippet
Array Stream
ArrayList Stream
Set Stream
LinkedList Stream


Measurement Code

Result 

Array 31 sec
ArrayList 31 sec
set 52 sec
linkedlist 106 sec

Result confirms the guess that Array based collections are fastest, so choose right datastructure before you start using parallel streams.

Code used in blog is available @ github

what is new in java8 ConcurrentHashMap

Java8 has lots of new features that will help in writing code that express its intent more clearly and in concise way.

ConcurrentHashMap has lots of nice features that reduces boiler plate code, most of the new features are parallel, so you don't have to worry about locks/threads etc when using CHM.

Smart Cache

One of the most common usage of CHM is to build cache and it has little concurrency issue that value for key should be computed once and it should provide all the "happens after" guarantee.

Pre JDK8 you have to do some thing like 

JDK8 has special function computeIfAbsent for such type of thing

Difference is obvious for prejdk8 future task is required and some other special handling to make sure it works fine, but JDK8 just call to computeIfAbsent with lamdba expression and your are done.
There is computeIfPresent function also to remap/refresh value in cache.

Merge values 
One of the most common problem with maps is when values of same keys needs to merged, one of the example is you have map of word & count.
Every time word is added to map and if it exists then count needs to be incremented

Example code pre JDK8

Example code in JDK8

All the noise that was there in JDK7 code is removed and code express its intent so nicely

 Aggregate/Reduce values

This is also very common use case where single value is derived from values in map for eg total number of words

sample code for pre JDK8

sample code for JDK8



Code is so so much clean, extra thing to note in jdk8 reduce function is first parameter which is the (estimated) number of elements needed for this operation to be executed in parallel.
So this function supports parallel reducing

Iteration
All the collection of JDK8 has done improvement on iteration method, so application code will never have any loop, it is all controlled by underlying collection and due to which iteration can be done in parallel .

CHM has 2 types of foreach

others interesting functions are search

One thing to note is that all the parallel function are executed on common forkjoin pool, there is way by which you can provide your own pool to execute task.

Recommend books @ agile singapore

I recently attended agilesingapore conference. This was my first agile conference, lot to take away.
Amazing speakers were invited, keynote talks were very amazing and inspirational.

One of the things that you get from such type of conference is books recommendation. Lots of books were recommended. I only remember few of them.

I want to put it somewhere so that i can start making my read list for next couple of months.


Mindset: The New Psychology of Success

Fearless Change: Patterns for Introducing New Ideas  

101 Things I Learned in Architecture School

The Timeless Way of Building

Software Craftsmanship: The New Imperative

The Laws of Simplicity (Simplicity: Design, Technology, Business, Life)

97 Things Every Programmer Should Know: Collective Wisdom from the Experts

Growing Object-Oriented Software, Guided by Tests

Extreme Programming Explained: Embrace Change

The Click Moment: Seizing Opportunity in an Unpredictable World

The Fifth Discipline: The Art & Practice of The Learning Organization

Joy, Inc.: How We Built a Workplace People Love


Lot of books to read i have to start taking timeout out from my so called busy schedule!

Factory Without IF-ELSE

Object Oriented Language has very powerful feature of Polymorphism, it is used to remove if/else or switch case in code.

Code without condition is easy to read. There are some places where you have to put them and one of such example is Factory/ServiceProvider class.

I am sure you have seen factory class with IF-ELSEIF which keeps on getting big.

In this blog i will share some techniques that you can be used to remove condition in factory class.

I will use below code snippet as example

Reflection
This is first thing that comes to mind when you want to remove conditions. You get the feeling of framework developer!



This looks very simple but only problem is caller has to remember fully qualified class name and some time it could be issue.

Map
Map can be used to to map actual class instance to some user friendly name

This also looks neat without overhead of reflection.

Enum
This is interesting one

This method is using enum method to remove condition, one of the issue is that you need Enum for each type. You don't want to create tons of them!
I personally like this method.

 Conclusion
If-else or switch case makes code difficult to understand, we should try to avoid them as much as possible. Language construct should be used to avoid some of switch case.

We should try to code without IF-ELSE and that will force us to come up with better solution.