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GPars: Groovy Parallelism for Java
The document discusses the concepts of concurrency and parallelism in programming, focusing on Groovy and Java technologies. It emphasizes that improper use of locks can hinder parallel performance, contrasting it with Java 8's functional programming features that simplify thread management. The content also explores various software architectures and techniques for improving performance through parallel processing.
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GPars: Groovy Parallelism for Java
- 1. Groovy Parallelism forJava Prof Russel Winder Director It'z Interactive Ltd e: russel@itzinteractive.com e: russel@winder.org.uk t: @russel_winder
- 2. Prof Russel Winder ■ Company director, independent consultant, analyst, author, expert witness, trainer, mentor,… ■ Involved with GPars, Groovy, Gant, Gradle, GroovyFX, Python, SCons ■ Ex-theoretical physicist, ex-UNIX systems programmer, ex-computer science academic. Still human.
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- 5. Concurrency ■ Atechnique for doing lots of little bits of work, one at a time, and then leaving them for later. ■ Co-routines.
- 6. Concurrency ■ Concurrencyis also a technique for simulating parallelism on a uni-processor. ■ Time-division multiplexing.
- 7. Concurrency ■ Locks,semaphores, monitors all introduced to manage shared mutable memory in the presence of concurrency. ■ Operating systems techniques.
- 8. Parallelism ■ Havingmore than one thing happening at the same time: multiple processors or cores working on a single program at the same time. ■ The only reason for using parallelism is to make computations take less time.
- 13. Observation ■ Squirrelsuse locks when managing their food resources.
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- 15. Question ■ Whois interested in harnessing parallelism for performance improvement?
- 16. Question ■ Whouses synchronized in Java?
- 17. Question ■ Whouses synchronized in Java? You are doing it wrong.
- 18. Question (with subsidiaries) ■ Who uses explicit locks in Java? ■ Who is not using java.util.concurrent? ■ Who is using java.util.concurrent?
- 19. Question (with subsidiaries) ■ Who uses explicit locks in Java? ■ Who is not using java.util.concurrent? ■ Who is using java.util.concurrent? You are definitely doing it wrong.
- 20. Rationale ■ Thepurpose of locks is to prevent parallelism. ■ Locks prevent performance improvement.
- 21. Consequence ■ Squirrelsdeny parallelism of consumption. ■ Squirrels deny performance improvement.
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- 23. Forward Looking Can Java 8 make things better?
- 24. Java 8 Streams ■ Internal rather than external iteration. ■ Functional programming approaches. ■ Threads as infrastructure. This is the real “biggy”, programmers do not explicitly manage threads.
- 25. Example π
- 26. What is thevalue of π ? ■ Easy, it's π obviously. It's simples Александр Орлов 2009
- 27. Approximating π ? ■ Find an estimate of the value of π. 11 =∫0 dx ■ Approximate an integration with a 4 1x 2 summation. 4 n 1 π≈ ∑i=1 n i−0.5 2 1+( ) n
- 28. Quadrature Sumall the areas of the rectangles. Addition is associative and commutative. a + b + c + d = (a + b) + (c + d) Can sum partial sums. Embarrassingly parallel
- 29. Parallelism Scatter/gather Farmer/worker Fork/join Map/reduce
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- 31. Software Architectures Actors Independent Dataflow processes Operators connected communicating via by channels with asynchronous activity triggered by exchange of arrival of data on the messages. channels. Data Parallel Transform a sequence to CSP another sequence where Sequential processes all individual actions connected by channels happen at the same time. using synchronous message exchange (rendezvous).
- 32. Software Architectures Data Parallel Transform a sequence to another sequence where all individual actions happen at the same time.
- 33. Software Architectures Actors Independent processes communicating via asynchronous exchange of messages.
- 34. Software Architectures Dataflow Operators connected by channels with activity triggered by arrival of data on the channels.
- 35. Software Architectures CSP Sequential processes connected by channels using synchronous message exchange (rendezvous).
- 36. Software Architectures Active Objects Fork/Join An object that is An toolkit for tree structured actually an actor but concurrency and looks like a full parallelism. service object. Agents A wrapper for some Software Transactional shared mutable state. Memory Wrappers for mutable values that uses transactions rather than locks.
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- 38. Mantra ■ Squirrelsdeny parallelism. ■ Squirrels deny performance improvement. ■ Programmers' code should not emulate squirrel behaviour.
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- 41. Source Code The sample codes are in a Git repository on GitHub and my own website.
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- 44. Groovy Parallelism forJava Prof Russel Winder Director It'z Interactive Ltd e: russel@itzinteractive.com e: russel@winder.org.uk t: @russel_winder