August 2015
Intermediate to advanced
312 pages
7h 28m
Japanese
Content preview from 初めてのSpark
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.
219
10.9 まとめ
して並列度を指定できます。
10.8.3
ベージコレクンメモ
もう
1
つ問題になり得ることに、
Java
のガベージコレクションがあります。
Java
の並行
Mark-
Sweep
ガベージコレクタを有効にすれば、
GC
による予想外の大きな中断を最小限にとどめること
ができます。並行
Mark-Sweep
ガベージコレクタを使うと、全体的にリソースの消費は増大しま
すが、中断の回数を減らすことができます。
GC
は、
Spark
の設定パラメータの
spark.executor.extraJavaOptions
に
-XX:+UseConcMark
SweepGC
を追加すれば制御できます。
10-48
では、
spark-submit
でこのオプションを指定
しています。
10-48
Mark-Sweep
ー
spark-submit --conf spark.executor.extraJavaOptions=-XX:+UseConcMarkSweepGC App.jar
中断を生じにくくするガベージコレクタを使うことに加えて、
GC
のプレッシャーを下げるこ
とで大きな違いを生むことができます。
RDD
のキャッシングを、ネイティブのオブジェクトでは
なく、シリアライズされた形式で行うことも
GC
のプレッシャーを下げてくれます。そのため、
Spark Streaming
が生成する
RDD
は、シリアライズされた形式で保存されるのがデフォルトに
なっています。
Kryo
シリアライゼーションを使えば、キャッシュされたデータのメモリ内での表 ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.