◆ 並列処理
サンプルでActivatorというプロジェクト管理のライブラリを使っていたので、それを使用
（sbtと同様なもの）

Activatorのインストール
$ sudo brew install typesafe-activator

プロジェクトを作りたいディレクトリで下記実行（今回はminimal-scalaというものを使う）
AC-A-069:scala_prac2 *****$ sudo activator new
Password:

Enter an application name
> test3

The new application will be created in /Users/*****/Desktop/scala_prac2/test3

Enter a template name, or hit tab to see a list of possible templates
> minimal-scala
OK, application "test3" is being created using the "minimal-scala" template.

To run "test3" from the command-line, run:
/Users/*****/Desktop/scala_prac2/test3/activator run

To run the test for "test3" from the command-line, run:
/Users/*****/Desktop/scala_prac2/test3/activator test

To run the Activator UI for "test3" from the command-line, run:
/Users/*****/Desktop/scala_prac2/test3/activator ui

プロジェクトが作成されるので、そのディレクトリに移動
下記のように何もせずに実行すると、最初から入っているHelloWorldを出力するファイルが実行される
MAC-A-069:scala_prac2 *****$ cd test3
MAC-A-069:test3 *****$ ls
LICENSE				activator-launch-1.0.0.jar	project
activator			build.sbt			src
MAC-A-069:test3 *****$ sudo ./activator run
[info] Loading project definition from /Users/*****/Desktop/scala_prac2/test3/project
[warn] Multiple resolvers having different access mechanism configured with same name 'typesafe-ivy-releases'. To avoid conflict, Remove duplicate project resolvers (`resolvers`) or rename publishing resolver (`publishTo`).
[info] Updating {file:/Users/*****/Desktop/scala_prac2/test3/project/}test3-build...
[info] Resolving org.fusesource.jansi#jansi;1.4 ...
[info] Done updating.
[info] Set current project to test3 (in build file:/Users/*****/Desktop/scala_prac2/test3/)
[info] Updating {file:/Users/*****/Desktop/scala_prac2/test3/}test3...
[info] Resolving jline#jline;2.11 ...
[info] Done updating.
[info] Compiling 1 Scala source to /Users/*****/Desktop/scala_prac2/test3/target/scala-2.11/classes...
[info] Running com.example.Hello
Hello, world!
[success] Total time: 4 s, completed 2015/02/04 11:54:45

まず並列処理せず通常実行するプログラムと実行結果
プログラムはsrc/main/scala/com/example/に置く

package com.example

object Parallel {
        def main(args: Array[String]) {
                (1 to 10).map { i =>
                        println(i)
                        Thread.sleep(500)
                }
        }
}

MAC-A-069:test3 *****$ ./activator
[info] Loading project definition from /Users/*****/Desktop/scala_prac2/test3/project
[warn] Multiple resolvers having different access mechanism configured with same name 'typesafe-ivy-releases'. To avoid conflict, Remove duplicate project resolvers (`resolvers`) or rename publishing resolver (`publishTo`).
[info] Set current project to test3 (in build file:/Users/*****/Desktop/scala_prac2/test3/)
> runMain com.example.Parallel
[info] Compiling 1 Scala source to /Users/*****/Desktop/scala_prac2/test3/target/scala-2.11/classes...
[info] Running com.example.Parallel
1
2
3
4
5
6
7
8
9
10
[success] Total time: 9 s, completed 2015/02/04 12:07:26
> runMain com.example.Parallel
[info] Running com.example.Parallel
1
2
3
4
5
6
7
8
9
10
[success] Total time: 5 s, completed 2015/02/04 12:07:34

１度目はコンパイルするので少々遅いがその後は早い
今回は5秒で実行が終わる

次に並列処理

package com.example

object Parallel {
        def main(args: Array[String]) {
                (1 to 10).par.map { i =>
                        println(i)
                        Thread.sleep(500)
                }
        }
}

MAC-A-069:test3 *****$ ./activator
[info] Loading project definition from /Users/*****/Desktop/scala_prac2/test3/project
[warn] Multiple resolvers having different access mechanism configured with same name 'typesafe-ivy-releases'. To avoid conflict, Remove duplicate project resolvers (`resolvers`) or rename publishing resolver (`publishTo`).
[info] Set current project to test3 (in build file:/Users/*****/Desktop/scala_prac2/test3/)
> runMain com.example.Parallel
[info] Compiling 1 Scala source to /Users/*****/Desktop/scala_prac2/test3/target/scala-2.11/classes...
[info] Running com.example.Parallel
1
2
3
6
4
8
7
5
9
10
[success] Total time: 6 s, completed 2015/02/04 12:13:15
> runMain com.example.Parallel
[info] Running com.example.Parallel
1
3
8
6
2
7
4
9
5
10
[success] Total time: 2 s, completed 2015/02/04 12:13:18

ループ処理の際に.parをつけるとコレクション(今回は1~10が入ったmap)が並列コレクションに変換され並列処理される。
並列コレクションを使用すると、プログラムを実行しているPCのCPUコア数に応じてスレッドを分割して実行します（※並列化のコストも掛かるので、要素数や処理内容によっては遅くなることもあります）。
実際に並列処理すると通常５秒かかっていた処理が２秒で終わる。
ただ、順序がばらばらになるので注意