January 2018
Beginner to intermediate
234 pages
7h 8m
Chinese
Content preview from Kafka权威指南
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监控
Kafka
｜
175
在垃圾回收语义里，
Old
和
Full
的意思是一样的。我们需要监控这两个指标的
Collection
Count 和 CollectionTime 属性。CollectionCount 表示从
JVM
启动开始算起的垃圾回收次
数，CollectionTime 表示从
JVM
启动开始算起的垃圾回收时间，以
ms
为单位。因为这些
属性是计数器，所以它们可以告诉我们发生
GC
的次数和花费在
GC
上的时间，还可以用
于计算平均每次
GC
花费的时间，不过在通常的运维中，这样做并没有多大用处。
这些指标还有一个
LastGcInfo 属性。这是一个由
5
个字段组成的组合值，用于提供最后一
次
GC
的信息。其中最重要的一个值是 duration 值，它以
ms
为单位，展示最后一次
GC
花费的时间。其他几个值（GcThreadCount、id、startTime 和 endTime）虽然也会提供一些
信息，但用处不大。不过要注意的是，我们无法通过该属性查看到每一次
GC
的信息，因
为年轻代
GC
发生得很频繁。
2. Java
操作系统监控
JVM
通过
java.lang:type=OperatingSystem 提供了一些操作系统的信息，不过这些指标
的信息量很有限，并不能告知操作系统的完整状况。这些指标有两个比较有用但在操
作系统里难以收集到的属性——MaxFileDescriptorCount 和 OpenFileDescriptorCount。
MaxFileDescriptorCount 展示
JVM
能够打开的文件描述符 ...
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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.