Memory Analysis of Scala

Question

I understand that scala supports immutability and so when we if we have two integer vals and we do val1 + val2, so it will create a new integer which will have the value as val1 + val2.

My question is that because scala creates new instances of objects to not to mutate the previous object, what are the performance and memory drawbacks of immutability?

Edit: I want details specific to scala about how it deals with the performance and memory overheads.

Possible duplicate of [Can immutable be a memory hog?](http://stackoverflow.com/questions/2527412/can-immutable-be-a-memory-hog) — Michał, Nov 20 '16 at 11:33
@Michal, I am having this question specific to scala. What are the performance and memory enhancements that scala has internally to support immutability? — Maulik Soneji, Nov 20 '16 at 11:34

score 2 · Accepted Answer · answered Nov 20 '16 at 11:49

2

Scala code is compiled to JVM bytecode so basically memory management does not differ compared to Java. Chapter 6 of Programming in Scala, First Edition mentions potential trade-offs of using immutable memory. Potentially you may create many instances of objects but Scala libraries usually create short-lived objects so the garbage collector should deal with them quickly.

answered Nov 20 '16 at 11:49

Michał

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There are multiple implementations of Scala. Two are production-ready: Scala-JVM on the Java platform and Scala.js on the ECMAScript platform. Scala-native is in development, Scala.NET is abandoned. You are confusing the Scala Programming Language with one of the several Scala compilers. – Jörg W Mittag Nov 20 '16 at 11:51
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I see. The question never mentions any specific Scala implementation so i only about JVM which is most popular i believe. – Michał Nov 20 '16 at 11:53
@Michal, I think that your answer was helpful from the JVM perspective. Thanks for the answer. – Maulik Soneji Nov 20 '16 at 12:46

score 0 · Answer 2 · answered Nov 20 '16 at 17:50

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Note that, if you want, you can use var-s and mutable structures, which can, well, mutate. Examples:

var i = 1
i += 1
val l = mutable.Map(1 -> 5)
l += (2 -> 4)  // this one was writte from memory, may need a correction

answered Nov 20 '16 at 17:50

VasiliNovikov

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Memory Analysis of Scala

2 Answers2