groovy, gpars, @compilestatic and invokedynamic. and java 8

Copyright © 2014 Russel Winder 1

Groovy, GPars, @CompileStatic and invokedynamic. And Java 8.

Russel Winder

email: [email protected]: [email protected]

twitter: @russel_winder

http://www.russel.org.uk

mailto:[email protected]

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


is a programming language.


is a dynamic programming language.


Dynamic language rarely

exhibit high performance.


This is generally not a problem as

most dynamic languages are

usually used in I/O-bound contexts.


In CPU-bound contexts however,

it is a REAL problem.


The biggest issue for Groovy performance

is that floating point values are

BigDecimal by default.


We need an example.


What is the Value of ?

Easy, it's known exactly.

It's .

Obviously.


Putative joke involving Alexander Orlov (*)and the phrase It's simples. elided as UK“ ”television-related comedy doesn't travel.

(*) A fairly cute meerkat.


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 and

associative, 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

fork join

Data parallel


Back to the BigDecimal issue…


…to the code:


As with (almost) all programming language,

Groovy is focussed on sequential activity.


In a multicore world, we harness all the

cores to improve performance.


The Java Platform offers threads,

Java, and hence Groovy, can use them.


Shared memory multithreading is an

infrastructure technique.


java.util.concurrent


Concurrency can be used for

I/O-bound systems, but…


…concurrency can also be used

for CPU-bound systems.

Parallelism .


Parallelism is about performance.


Look at some code…


Dynamism and parallelism are

rarely good bedfellows.


@CompileStatic is about…

…eliding dynamism.…about performance.


invokedynamic is about…

…supporting dynamism.…performance.


Java 8

The greatest revolution ofJava since 1994.

A far bigger revolution ofJava than Java 5.


Java 8

Introduces various things, the most important of which are:

Lambda expressions.Default methods in interfaces.


Java 8

as a consequence oflambda expressions introduces:

Streams†.

† And parallelism, and parallelism is about performance.


More codes…


Needs You…


Groovy, GPars, @CompileStatic and invokedynamic. And Java 8

Russel Winder

email: [email protected]: [email protected]

twitter: @russel_winder

http://www.russel.org.uk

mailto:[email protected]

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

groovy, gpars, @compilestatic and invokedynamic. and java 8

Technology