May 2019
Intermediate to advanced
464 pages
9h 22m
Japanese
Content preview from Node.jsデザインパターン 第2版
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312
9
章 特殊な問題を解決するためのパターン
処理と比較して実行時間が
10%
減少したはずです。もちろんこれは多くの要因（受信したリクエスト数、
リクエスト間の時間間隔など）に依存します。バッチ処理に対するキャッシュ処理の利点は、リクエス
トの頻度が高くそれが長時間続く場合により重要になります。
関数呼び出しの結果をキャッシュしておくことを「メモ化（
memoization
）」と呼びます。
npm
では、多くのパッケージが非同期メモ化を実装しています。よくできたパッケージ
のひとつが
memoizee
（
https://npmjs.org/package/memoizee
）です。
9.2.3.2
キャッシュ処理機構の実装について
実社会のアプリケーションでは、より高度なキャッシュの無効化技法と保存メカニズムを使わねばな
らないかもしれません。それが必要になるのは次の理由からです。
●
大量の値がキャッシュされると、消費するメモリがふくれあがる。その場合、
LRU
（
Least
Recently Used
）アルゴリズムを用いればメモリ使用量を一定に維持できる
●
アプリケーションが複数のプロセスに分散している場合、キャッシュに単なる変数を使うと各
サーバのインスタンスから返される結果が異なる恐れがある。それが
望ましくなければ、キャッ
シュに共有領域を使うことができる。よく使われるのが
Redis
（
http://redis.io
）と
Memcached
（
http://memcached.org
）
●
キャッシュを時間
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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.