Yesterday, when I login to my VM I found that the disk is full. Even
a tab command completion cannot be done. I immediately delete some
unused files and the system works. However, when I reboot the system, it
stucked at
A start job is running for Create Volatile Files and Directories...:
按习惯在HOME中添加了.bashrc文件，定义一些alias和PS1，结果发现putty登录之后并未生效，还须手动source .bashrc，在~/目录增加.bash_profile或.profile解决：
半年前写过篇如何换启辉器和环形灯管，得，家里的老式日光灯又坏了，灯开着嗡嗡响，看起来像是镇流器出了问题，但环形灯管的头部也发黑了，灯的频闪也比较重，所以想买镇流器和灯管给换上。
老式荧光灯的构造比较复杂，启辉器+镇流器+灯管，T5/T8 22W
环形灯管20块左右，对应镇流器30块左右。用过日光灯的都知道，启辉器有多容易坏……花50块钱换一堆淘汰不禁用的东西，不大划算。
After I changed the HOME folder to another place, I copied the ssh config folder from old HOME to the new place. Supposedly it should directly work, right? However, when I login the server with my private key, the server said: "Server Refused Our Key"...
Unity supports three ways of registering types:
Typically, Instance registration and Type registration resolve
dependencies through ResolvedParameter<T>, while
Factory registration resolve dependencies by a factory delegate. In
practice, when you want to resolve a List<T> or
Dictionary<T1, T2>, Factory registration is what you
want. Let's go through how to resolve a collection of customized
classes.
SVM的函数间隔定义中会用到点到超平面距离的推导，《统计学习方法》中对此没有详细的解释，当然这个问题有许多解法，找到了一种比较直观的解法如下。
QuickSort 快速排序是常见的考察代码基本功面试题。简洁易读的实现可以一定程度展现面试者的代码功底。
算法导论对于快排讲解的很透彻，也有伪代码，即便如此，网上许多实现还是错的，不能通过一些边界用例，如数组已排序或数组中有重复元素的情况。还有一些用python的实现不满足原位排序(in-place)的要求，直接新建两个新List，这种方法其实也是取巧，简化了partition函数的实现难度。
Google Ads是许多独立博客赢利维持自身运转的方案之一。不过近些年前已经不大流行了，因为转化率低，没有很大的基础流量支持，其实很难赚到钱。独立博客的流量如果不做PR的话，主要还是靠搜索引擎。而提升流量的根本需要有对应的用户群，相较而言，微信公众号、头条号上的平台流量足够大，用户粘度更高，赢利方式也更为多样，对作者来说更易变现。现在这年头还玩独立博客的人，我想都是有一份自己的坚持，一块独立的领地，完全自由掌控的感觉，想靠这个赚钱还是算了。
言归正传，说说Google AdSense如何添加到博客里。
If you use Visual Studio 2017 and create an .NET Core projects the first time, the following errors might appear:
The current .NET SDK does not support targeting .NET Standard 2.0. Either target .NET Standard 1.6 or lower, or use a version of the .NET SDK that supports .NET Standard 2.0. XXXProject C:Files (x86)Visual Studio\2017.NET.Sdk.NET.TargetFrameworkInference.targets
Another related issue is .NET Core project load failed. Both errors point out that the corresponding .NET SDK is missing.
If you follow the instructions to install .NET Core SDK with a random version from here: https://aka.ms/dotnet-download . Most likely that the issue cannot be resolved.
Recently we use Grafana to monitor ASP.NET Core apps. We have an interesting observation that sometimes the "allocated memory" is larger than "working set". After investigation, we found the root cause is that the app uses native dlls which operates on unmanaged memory which is not managed by GC. Therefore, how to correctly collect memory related metrics in C#?
We will explain these related concepts in this post.