why go is an important programming language

Copyright © 2013 Russel Winder 1

Why Go is anImportant Language

Prof Russel Winder

email: [email protected]: [email protected]

twitter: russel_winder

mailto:[email protected]


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controversial adjective of, pertaining to, or characteristic of controversy; polemical


controversy noun dispute, argument, or debate, especially one concerning a matter about which there is strong disagreement


polemic noun a strong verbal or written attack on someone or something


Go, made public late 2009.


It's a better C.


Strong, static type checking.


Garbage collected.


Statically linked.


Aware of DVCS repositories.


No classes.


Separation of state and behaviour.


Focus on modern, multicore hardware.


Concurrency is a tool for structuring execution where asingle processor is used by multiple computations.

Parallelism is about making a computation completefaster than using a single processor.


Parallelism is performance improvement.

Performance improvement requires parallelism.


People should tremble in fear

at the prospect of using

mutableshared-memorymultithreading.


Locks deny parallelism.

The whole purpose of a lock is toprevent parallelism.


Locks are needed only ifthere is mutable shared state.


Avoid mutable shared state.


Use processes and message passing.


It's all easier if processesare single threaded.


Applications and tools programmersneed computational models with

integrated synchronization.


ActorsIndependent processes communicating via asynchronous exchange of messages

CSPSequential processes connected by channels using synchronous message exchange (rendezvous).

DataflowOperators connected by channels with activity triggered by arrival of data on the channels.

Data ParallelismTransform a sequence to another sequence where all individual actions happen at the same time.


Active ObjectsAn object that is actually an actor but looks like a full service object.

AgentsA wrapper for some shared mutable state.

Software Transactional MemoryWrappers for mutable values that uses transactions rather than locks.

Fork/JoinAn toolkit for tree structured concurrency and parallelism.


Example.


What is the Value of ?

Easy, it's known exactly.

It's .

Obviously.


It's simples Александр Орлов 2009


Approximating

● What is it's value represented as a floating point number?● We can only obtain an approximation.● A plethora of possible algorithms to choose from, a

popular one is to employ the following integral equation.

4=∫0

1 1

1x2dx


One Possible Algorithm

● Use quadrature to estimate the value of the integral – which is the area under the curve.

=4n∑i=1

n 1

1i−0.5n

2

With n = 3 not much to do, but potentially lots of error. Use n = 107 or n = 109?

Embarrassingly parallel.


Because addition is commutative andassociative, expression can be

decomposed into sums of partial sums.


a + b + c + d + e + f

=

( a + b ) + ( c + d ) + ( e + f )


Scatter – Gather

map reduce


Code!


If you want the code, clone the Git repository:

http://www.russel.org.uk/Git/Pi_Quadrature.git


Or if you just want to browse:

http://www.russel.org.uk/gitweb

http://www.russel.org.uk/gitweb


Multicore and multiprocessor are nowthe norm, not the exception.


Parallelism only matters ifcomputational performance matters.


Unstructured synchronizationof concurrent systems

is not a feasible approach.


Actors, CSP, Dataflow, andData parallelismare the future of

applications structure.


Passing messages betweenprocesses is the way forward.


Shared memory concurrencyis a dead end for applications.


Goroutines

and

channels


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Why Go is anImportant Language

Prof Russel Winder

email: [email protected]: [email protected]

twitter: russel_winder

mailto:[email protected]

why go is an important programming language

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