programmers do not favor lambda expressions for concurrent ... · functional elements in...

Otto-von-Guericke University Magdeburg, GermanyChair of Software Engineering

November 6th, 201826th ACM Joint European Software Engineering Conference and Symposium on the Foundations of

Software Engineering (ESEC/FSE), Lake Buena Vista, Florida, USA

Programmers do not Favor Lambda Expressions for Concurrent Object-Oriented

Code

Sebastian Nielebock Robert Heumüller Frank Ortmeier

/ 07.11.2018 Chair of Software Engineering

• Trend of incorporation of functional elements Multi-paradigm languages: Scala, Python

Functional elements in OO-languages: Java 8 (Lambda expressions and streams)

• Simpler programming Defining and combining simple functions

Pure programming = no side effects/context information

immutability

More concise code:A Comparative Study of Programming Languages in Rosetta Code –

ICSE’15 - S. Nanz and C. A. Furia

Functional Programming in other Languages


• Anonymous functions with simple local functionality

• Incorporated by most major OO-programming languages• C# - since C# 3.0 in 2007

• C++ - since C++11 in 2011

• Java - since Java 8 since 2014

Lambda Expressions

public static void main(String... args){

int[] numbersArray = {0,1,2,3,4,5,6,7,8,9,10};

Arrays.stream(numbersArray)

.filter(n -> n%2==0).map(en -> 3*en+1)

.forEach(System.out::println);

}


• Concurrency ≠ Parallelism (Talk by Rob Pike) Code that can potentially run in parallel

• Benefits less boilerplate code

original lambda expressions do not introduce side effects

Lambda expressions facilitate concurrent development

Lambda Expressions in Concurrent Code


• Facilitation hardly measurable

• Frequency as an indicator of facilitation 𝐹𝑎𝑐𝑖𝑙𝑖𝑡𝑎𝑡𝑖𝑜𝑛 → 𝐹𝑟𝑒𝑞𝑢𝑒𝑛𝑐𝑦

• Low frequency either no facilitation or

another diminishing factor

Measurement


= Lambda expressions using outer context in their bodies

• Problems in concurrent programming:

Capturing Lambda Expressions/Closures

for (int i = 0; i < 10; i++)

{

new Thread(

() => Console.Write(i + " ")).Start();

}

// output: 4 4 4 4 5 7 9 9 9 10

for (int i = 0; i < 10; i++)

{

new Thread(

value => Console.Write(value + " ")).Start(i);

}

// output: 0 1 3 2 4 6 5 7 8 9


1. Frequency of lambda expressions in concurrent contexts• Differences between C#, C++, Java

2. Ratio of capturing to non-capturing lambda in concurrency

3. Other use cases apart from concurrency

Research Questions


Study

Project Selection

GitHub Stars

ParsingCode

ANTLR parser, CDT, JDT

ConcurrentContext

Lambda Expression

• Analysis ofimports andparent nodeswith keywords

Files

Use Cases

• AST-node types• Capturing

lambdas: Analysis for non-local variables

• Semi-automaticfile name mapping

1000 projects for eachprogramming language in

C#, C++, and Java

2923 projects


• 𝑖𝑛𝑡𝑒𝑛𝑠𝑖𝑡𝑦 𝑝 =𝑛𝑢𝑚𝑏𝑒𝑟𝐿𝑎𝑚𝑏𝑑𝑎𝐼𝑛𝐶𝑜𝑛𝑐𝐶𝑜𝑛𝑡𝑒𝑥𝑡(𝑝)

𝑛𝑢𝑚𝑏𝑒𝑟𝐿𝑎𝑚𝑏𝑑𝑎(𝑝)

Results Frequency I

*only 1597 projectsthat use lambdaexpressions


• 𝑢𝑡𝑖𝑙𝑖𝑧𝑎𝑡𝑖𝑜𝑛 𝑝 =𝑛𝑢𝑚𝑏𝑒𝑟𝐹𝑖𝑙𝑒𝑠𝑊𝑖𝑡ℎ𝐿𝑎𝑚𝑏𝑑𝑎𝐼𝑛𝐶𝑜𝑛𝑐𝐶𝑜𝑛𝑡𝑒𝑥𝑡(𝑝)

𝑛𝑢𝑚𝑏𝑒𝑟𝐹𝑖𝑙𝑒𝑠𝑊𝑖𝑡ℎ𝐶𝑜𝑛𝑐𝐶𝑜𝑛𝑡𝑒𝑥𝑡(𝑝)

Results Frequency II

*only 1399 projectsthat use concurrentcontexts andlambda expressions


Results - Capturing Lambda Expressions


Results – Other Use Cases


• Higher intensity/utilization in C# Refactoring mechanisms for other programming languages

• Capturing lambda expressions as a diminishing factor Detect/Repair Misuses of the functional programming API in OO-

languages

Other problems?

• Other use cases as testing and algorithmics automatic refactorings for these use cases?

Implications


Thank you for your attention!

Sebastian Nielebock

Mail: [email protected]

Web: https://cse.cs.ovgu.de/cse/members/sebastian-nielebock/

Replication of our results:

http://dx.doi.org/10.1007/s10664-018-9622-9

https://bitbucket.org/SNielebock/lambdainconcurrentdataset

mailto:[email protected]

https://cse.cs.ovgu.de/cse/members/sebastian-nielebock/



Appendix


atomic

concurrent

future

parallel

runnable

sync

thread

Concurrency Keywords


Use Case Keywords

Algorithmic - Implementation of an Algorithm

algorithm, calc, search, script, analyze, util, helper, manager, cluster, generate, generation, generator, optimize,optimization, visitor, process, select, service, factory, provider, operate, operation, operator, find, tracker, mutation, mutate, mutator, compute, backend, sort

Composition - Composition or Decomposition of Data

composition, spawn, multiplexer, serializer, compose, split, join, build, combine, combinator

Configuration - Configuration of the Software

config, setting, info, readme, version, option, default

DataStorage – Database Actions data, storage, cache, sql, query, queries

Datastructure - Implementation of Data Structures

array, list, map, tree, string, object, graph, heap, stack, table, queue, node, template, matrix, vector, collect, set, item, unit, type, entity, enum, container, element, model

Use Cases Keywords I


Use Case Keywords

Embedded Programming hardware, camera, keyboard, mouse, memory, embedded, device, cpu, x86, x64

ExceptionHandling exception, error, warn, crash, bug, check, undefined

FileHandling file, directory, writer, reader

Graphical – visualization and graphical elements

graphical, color, pixel, gpu, render, light, texture, image, picture, shadow, draw, animation, animate, fade, geometry, point, scene, line, polygon, square, rectangle, circle, shape, visualisize, visualizer, ellipse, paint

Logging log

MultiMedia - video or audio management

audio, video, media, player, touch, virtual, recognize, gesture, codec

MultiThreading – parallel or concurrent implementation

thread, parallel, concurrent, sync, block, schedule, wait, handle, runtime, semaphore, event, signal, task, callback, callable, dispatch, mutex, suspend, job, sleep, timer

Use Cases Keywords II


Use Case Keywords

Network - web application net, server, client, remote, middleman, http, chat, distributed, delegate, request, timeout, message, share, sharing, socket, connect, receive, send, traffic, cookie, connection, cloud, ping, session, download, web, host, url, dns

Security security, authenticate, authentication, account, crypt

Test - automatic softwaretesting

test, benchmark, assert

TextManagement – textprocessing applications

string, character, document, parser, parse, csv, json, xml, scan, format, translation, translate, encoding, encode, decoding, decode, utf8, ascii, word

UI - user interface gui, widget, view, shell, display, button, canvas, editor, console, popup, bar, frame, scrollbar, window, about, listener, menu, command, action, layout, box, frontend

Use Cases Keywords III


Overview Projects with Lambda


Overview Projects with Concurrency


Overview Projects with Lambda and Conc.


Utilization – Projects with Concurrency


Use Cases C#


Use Cases C++


Use Cases Comparison

programmers do not favor lambda expressions for concurrent ... · functional elements in...

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