DZone
Thanks for visiting DZone today,
Edit Profile
  • Manage Email Subscriptions
  • How to Post to DZone
  • Article Submission Guidelines
Sign Out View Profile
  • Post an Article
  • Manage My Drafts
Over 2 million developers have joined DZone.
Log In / Join
Refcards Trend Reports Events Over 2 million developers have joined DZone. Join Today! Thanks for visiting DZone today,
Edit Profile Manage Email Subscriptions Moderation Admin Console How to Post to DZone Article Submission Guidelines
View Profile
Sign Out
Refcards
Trend Reports
Events
Zones
Culture and Methodologies Agile Career Development Methodologies Team Management
Data Engineering AI/ML Big Data Data Databases IoT
Software Design and Architecture Cloud Architecture Containers Integration Microservices Performance Security
Coding Frameworks Java JavaScript Languages Tools
Testing, Deployment, and Maintenance Deployment DevOps and CI/CD Maintenance Monitoring and Observability Testing, Tools, and Frameworks
Culture and Methodologies
Agile Career Development Methodologies Team Management
Data Engineering
AI/ML Big Data Data Databases IoT
Software Design and Architecture
Cloud Architecture Containers Integration Microservices Performance Security
Coding
Frameworks Java JavaScript Languages Tools
Testing, Deployment, and Maintenance
Deployment DevOps and CI/CD Maintenance Monitoring and Observability Testing, Tools, and Frameworks
  1. DZone
  2. Coding
  3. Languages
  4. Loop Performance in Groovy

Loop Performance in Groovy

Learn more about measuring loop performance in Groovy.

Dominik Przybysz user avatar by
Dominik Przybysz
·
Jan. 15, 19 · Presentation
Like (2)
Save
Tweet
Share
9.02K Views

Join the DZone community and get the full member experience.

Join For Free

In the 2018 Advent of Code challenged, I solved all the puzzles in Groovy. It is pretty obvious that choosing a good data structure is the most important part of obtaining a performant solution. However, the way we iterate over those structures is also very significant, at least when using Groovy.

Measuring Performance

I want to measure how long it takes to sum some numbers. For the performance testing of loops, I prepared a small function that simply sums some numbers:

void printAddingTime(String message, long to, Closure<Long> adder) {
    LocalTime start = LocalTime.now()
    long sum = adder(to)
    println("$message: $sum calculated in ${Duration.between(start, LocalTime.now()).toMillis()} ms")
}


Pseudo code for summing functions is below:

for i = 1 to n
  for j = 1 to n
    sum += i * j
  end
end


Loop Types

Let's implement the summing function in various ways.

collect and sum

First, the loop type is to use built-in (by Groovy) function collect and sum on collections (Range it this example):

(1..n).collect { long i ->
  (1..n).collect { long j ->
    i * j
  }.sum()
}.sum()


each

Next, let's write the same function using the each built-in function on collections (Range it this example) and then add results to accumulator variable:

long sum = 0
(1..n).each { long i ->
    (1..n).each { long j ->
        sum += i * j
    }
}
return sum


times

Now, instead of using each, we could use the function times built-in on Number by Groovy:

long sum = 0
n.times { long i ->
  n.times { long j ->
    sum += (i + 1)*(j+1)
  }
}
return sum


We have to add 1 to i and j because times generates numbers from 0 to n exclusive.


LongStream With sum

Java 8 came with a new feature — streams. One example of streams is LongStream. Fortunately, it has asum built-in function, which we can use:

LongStream.range(0, n).map { i ->
    LongStream.range(0, n).map { j ->
        (i + 1) * (j + 1)
    }.sum()
}.sum()


LongStream generates numbers in the same way as times function, so we also have to add 1 to i and j here.

LongStream With Manual Sum

Instead of sum function on LongStream, we can add all numbers manually:

long sum = 0
LongStream.range(0, n).forEach { i ->
    LongStream.range(0, n).forEach { j ->
        sum += (i + 1) * (j + 1)
    }
}
return sum


while

Of course, since Groovy inherits a big part of its syntax from Java, we can use the while loop:

long sum = 0
long i = 1
while(i <= n){
    long j = 1
    while(j <= n){
        sum+= i*j
        ++j
    }
    ++i
}
return sum


for

As we can use while, we can also use for loop in Groovy:

long sum = 0
for (long i = 1; i <= n; ++i) {
    for (long j = 1; j <= n; ++j) {
        sum += i * j
    }
}
return sum


Results

For my tests, I ran on Java 1.8 and Groovy 2.5.5. Script loops.groovy was fired using bash script:

#!/bin/sh
for x in 10 100 1000 10000 100000; do
  echo $x
  groovy loops.groovy $x
  echo
done


Values are in milliseconds:

Loop  n 10 100 1000 10000 100000
collect + sum 7 22 216 16244 1546822
each 12 17 118 7332 706781
times 2 10 109 8264 708684
LongStream + sum 7 17 127 7679 763341
LongStream + manual sum 18 35 149 6857 680804
while 8 20 103 3166 301967
for 7 10 25 359 27966


As you can spot, although the small number of iterations using built-in Groovy functions is good enough, for a much bigger amount of iterations, we should use while or for loops as in plain, old Java.

Code for these examples is available here. You can run those examples on your machine and check performance on your own. 

Happy looping!

Groovy (programming language)

Published at DZone with permission of Dominik Przybysz. See the original article here.

Opinions expressed by DZone contributors are their own.

Popular on DZone

  • Multi-Cloud Database Deep Dive
  • The New DevOps Performance Clusters
  • 3 Ways That You Can Operate Record Beyond DTO [Video]
  • Hackerman [Comic]

Comments

Partner Resources

X

ABOUT US

  • About DZone
  • Send feedback
  • Careers
  • Sitemap

ADVERTISE

  • Advertise with DZone

CONTRIBUTE ON DZONE

  • Article Submission Guidelines
  • Become a Contributor
  • Visit the Writers' Zone

LEGAL

  • Terms of Service
  • Privacy Policy

CONTACT US

  • 600 Park Offices Drive
  • Suite 300
  • Durham, NC 27709
  • support@dzone.com
  • +1 (919) 678-0300

Let's be friends: