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  combining dwarf failed: unknown load command 0x80000034 solution in GoLang

In case there is below error encountered while running some go program: combining dwarf failed: unknown load command 0x80000034 This may be due to that you are running go 1.16 on a Mac M! machine. If you go to check go version, it may tell you that you are running an arm version of go. go version go1.16.10 darwin/arm64 In such cases, you can try below methods to workaround the issue. Try to upgrade the go version to 1.17 and run the code again. If this is not an option for you because you have t...

   GO 1.16,0X80000034     2021-11-25 07:11:28

  Select top 3 values from each group in a table with SQL

Yesterday, my friend Liu Bing asked me a question about how to select top 3 values for each person in a database table using SQL. I think this question is interesting and it deserves some thoughts. Here I record down how to solve this issue. Assume we have a table which has two columns, one column contains the names of some people and the other column contains some values related to each person. One person can have more than one value. Each value has a numeric type. The question is we want to se...

   SQL,Correlated query,top 3     2013-05-23 03:21:25

  Introducing the for-if anti-pattern

Over the years, I've seen a bunch of coding anti-patterns. I figured maybe I'll share a few. Today, I'll introduce what I'm calling the for-if anti-pattern, also known as "We'll sell you the whole seat, but you'll only need the edge." This is a special case of the for-case anti-pattern, where all but one of the cases is null. for (int i = 0; i < 100; i++) { if (i == 42) { do_something(i); } } This can naturally be simplified to do_something(42); The for-if anti-pattern arises in ma...

   Programming,Anti-pattern,for-if,efficiency     2012-02-02 10:18:15

  A simple tutorial on Linux nohup command

In our daily work, there might be need to run some important program for hours or even days without being abruptly terminated. In such case, we may want to run the program with command nohup. nohup is the abbreviation of no hangup, i.e, don't hang up or terminate the process. This command will tell the process to ignore the system HUP signal. The HUP signal will be emitted when the terminal is exited or disconnected. Normally process will abort its execution when receiving this signal.  Bas...

   NOHUP,LINUX     2020-08-08 01:14:50

  do {...} while (0) in macros

If you are a C programmer, you must be familiar with macros. They are powerful and can help you ease your work if used correctly. However, if you don't define macros carefully, they may bite you and drive you crazy. In many C programs, you may see a special macro definition which may seem not so straightforward. Here is one example: #define __set_task_state(tsk, state_value) \ do { (tsk)->state = (state_value); } while (0) There are many this kind of macros which uses do{...}while(0)...

   C,macro,C++     2014-01-23 07:16:13

  How to check whether a struct implements an interface in GoLang

Unlike other programming languages like Java, when implementing an interface in GoLang, there is no syntax like below to explicit tell the relationship: type I interface { } type A struct implements I { } When looking at the code or running the code in GoLang, it might lead to a case one doesn't know whether a struct implements interface before trying to use it as some interface. According to GoLang spec, as long as a struct implements all functions of an interface, it is considered as having i...

   GOLANG,INTERFACE,IMPLEMENTATION,CHECK     2020-05-03 00:05:54

  New function signal.NotifyContext in GoLang 1.16

os/signal package in GoLang may not be frequently used but it provides some good features like Shutdown() which can be used to gracefully shutdown a running HTTP server. func (srv *Server) Shutdown(ctx context.Context) error With this function, there is no need to use third party library to gracefully shutdown HTTP server. How is it being used? package main import ( "context" "fmt" "net/http" "os" "os/signal" "time" ) func main() { server := http.Server{ Addr: ":8080", } http.Handl...

   GOLANG,NOTIFYCONTEXT,GRACEFUL SHUTDOWN     2021-06-19 01:07:10

  GoLang to build smaller executable file

Normally the executable file built with go is a bit large, it is always desired that a smaller executable file should be generated though. In this post, a couple of ways to reduce the size of the executable will be introduced. The end effect is that the executable file size would be much less than the normal generated one. The file which is built normally has below size. Mode LastWriteTime Length Name ---- ------------- ------ ---- -a---- 12/14...

   GOLANG,EXECUTABLE     2019-12-13 20:10:45

  static nested and non-static nested class in Java

Nested classes are divided into two categories: static and non-static(inner). Nested classes that are declared static are simply called static nested classes. Non-static nested classes are called inner classes. Static class can be defined as : class OuterClass{ static class StaticNestedClass{ //OTHER STUFF } } Static nested classes are accessed using the enclosing class name: OuterClass.StaticNestedClass For example, to create an object for the static nested class, use this synta...

   Java,static nested class,inner class     2014-04-23 07:11:44

  What are the Four Most Important Technologies Inside an Office, Today?

The office life has changed a lot since the beginning of the 21st century. Nowadays, technologies have taken over a large part of the work that people have to do, inside their walls. Some of them are more important than others, though. Here are four that no company should live without.  A VoIP Phone System If a company wants to communicate with its clients, it needs to install a centralized phone system. The old ones were complicated and costly. The more phone lines you had, the higher the ...

   SMARTPHONE,VOIP,5G     2022-12-24 06:35:02

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