Technical concepts

• APIs
• Database(SQL vs NoSQL)
• Scaling
• CAP Theorem
• Web authentication and basic security
• Load balancers
• Caching
• Message queues
• Indexing
• Failover
• Replication
• Consistent hashing

APIs

RESTful

RPC

SQL vs NoSQL

Scaling

Cache

Indexing

In order to improve the efficient to fetch a item from a large database, we use index.

Replication

Consistent hashing

概述

串讲，是以会议形式，串讲人给同事讲一个topic。会上的其他同事，对串讲人进行相关知识的提问，以考查其对此topic的掌握程度。便于尽快上手，投入工作。

程序开发设计

专业团队

技术范围：PHP，Go，Python，C/C++，JavaScript等

服务内容：系统设计，网站建设，服务集群搭建，数据采集，Office办公自动化，大学生毕设，进大厂模拟面试

问题

在Centos7系统上安装snap，遇到的问题记录

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[centos@ip-172-26-6-67 ~]$ sudo snap install core
error: system does not fully support snapd: cannot mount squashfs image using "squashfs": -----
       mount: wrong fs type, bad option, bad superblock on /dev/loop0,

       missing codepage or helper program, or other error

       In some cases useful info is found in syslog - try
       dmesg | tail or so.

       -----

Google一圈之后，解决方案如下：

Hugo is a framework written with Golang for building website.

I told my wife I wrote something on my blog. After heard that, she said she wants to build a blog and start writing. So I spent a few hours on setting up a local hugo site and deployed it on Github pages.

Here are all the thing you need to do:

• A github account, if you didn’t have one, you need to sign up
• Git installed on your local machine
• Install hugo
• Head over to GitHub and create a new public repository named username.github.io, where username is your username (or organization name) on GitHub
• Generate a website on local machine
• Push your local reposity to github
• Add a github workflow
• Config reposity’s page setting

If everything goes well, you will see your blog online https://YourGithubUsername.github.io/

背景

从拥有自己的第一台电脑至今，由于工作或其他原因，我已经换过好几台电脑。每一次拿到新电脑的第一件事，就是安装各种软件以及配置开发环境。手动下载，安装，这些工作其实完全可以自动化。 本篇文章持续记录自己工作和生活中用到的软件，最终目标，可以在新电脑上（Mac OS)能够一键安装所需的软件。

让我们来对服务器做一下压力测试吧！
本篇文章讲一下压力测试应该怎么做，压力测试过程中需要注意哪些指标，以及需要注意的事项。
首先，我们要清楚我们进行压测的目的是什么。是为了找出服务的性能瓶颈，还是为了检验当前服务能否扛住xxx量的并发？ 俗话说，“不打无准备之仗”，首先要根据压测目的出一个可行的书面方案。
下面是一个方案模板

This article keep tracks of the most used commands of GDB

Write a classic C program with your favoriate editor and save it as main.c.

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#include <stdio.h>

int main(int argc, char *argv[]) {
    printf("Hello world\n");
}

Compile it with gcc, which is a popular c/c++ compiler on linux.

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gcc -o main -g main.c 

Debug with gdb

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gdb main      // gdb programname -p [pid]

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(gdb) b main  // set breakpoint
(gdb) layout src // gui
(gdb) p  // print p/x hex
(gdb) i b // list all breakpoints, you can list other info

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┌─test.c───────────────────────────────────────────────────┐
│   3           int main(int argc, char *argv[]) {         │
│B+>4               printf("Hello world\n");               │
│   5           }                                          │
└──────────────────────────────────────────────────────────┘
process 31551 In: main             L4    PC: 0x555555555144
(gdb) r
Starting program: /home/junxxx/Workspace/the_c_language/test


Breakpoint 1, main (argc=1, argv=0x7fffffffe338)
    at test.c:4
(gdb)

Reference

1. Debugging with GDB

前言

本文记录“玩”Vim的经验，学习Vim是一件起步很困难的事，但是当你稍微熟悉它的操作模式之后， 会对它爱不释手。

学习，或者换句话说，玩Vim，最重要的是实际上手去用，去玩，去实操。心态放平衡，不要想着一口气学完所有的技巧并掌握它，事实上，作为一款编辑器，只要它能满足你的实际需求就行，你平常用不到的那些高级特性，可以在你日后慢慢使用的过程中逐渐去尝试。

Learn a shell a day, master Unix one day!

Pipe

Process read previous process’s output as its input and generate output to next process’s input. Use symbol | to create a pipeline, which a powerful skill in Unix.

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// count the numbers of text file in current directory.
ls -la | grep *.txt | wc -l

Xargs

Many programs, takes its arguments from the command line (char *argv[]) but ignores standard input fd 0. If you want to pipe the output of a program to input of another program that ignores standard input, like rm, you need to use xargs.