July 2019
Intermediate to advanced
480 pages
9h 35m
Chinese
Content preview from 持續交付｜使用Java
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| 第四章
容器帶來的挑戰
使用容器技術最大的挑戰就是學習曲線。這種技術不但與雲端和 PaaS 有很大的不同，
也是一種新興且不斷演變的技術。有時維持最新的容器創新技術甚至是一項全職的工
作。它的另一個主要挑戰是當舊的技術（包括 JVM 本身）在容器內運行時，不一定都
會正確或如預期地運作，你通常需要具備（至少要有基本的）運維知識才可能找出、了
解與修正問題。
在
Docker
內運行
Java
：
Daniel
經常遇到的陷阱
我參加過許多使用 Java 與 Docker 專案，我和我的團隊也克服了許多
不少問題。我曾經在2015 年的JavaOne 跟 IBM Cloud Runtimes 的
Developer Advocate 一起演說“Debugging Java Apps In Containers:
No Heavy Welding Gear Required”（
http://bit.ly/2DxYdzm
），以下是一些
挑戰與問題的摘要：
• 每一個 Java 9 之前的 Java 執行環境都不知道控制群組（cgroup）。
當你索取 app 可用的 CPU 核心數量時，它會回傳底層主機的 CPU 資
源資訊，事實上，這些資源可能被多個在同一台主機上運行的容器共
用。這也會影響一些 Java 執行環境屬性，因為 fork-join pool 與記憶
體回收參數都是根據這項資訊來設置的。你可以在啟動 JVM 時，用
命令列旗標設定資源限制來克服這個問題。
• 容器通常共用主機上的單一熵源（source ...
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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.
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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.