How to use constants in Golang
What is a Constant or Const in Golang? Here's what you need to know about using constants in Go.
In Go language, select statement is like switch statement , but in select statement, case statement refers to communication, i.e. sending or receiving operation on channel.
Syntax:
select{
case SendOrReceive1: // Lệnh
case SendOrReceive2: // Lệnh
case SendOrReceive3: // Lệnh
.......
default: // Lệnh
In this article, we will learn how to use default case to avoid deadlock. But first, we will learn what is deadlock case when using select command in Golang ?
Things to know about deadlock case in Golang
Deadlock: When you try to read or write data from a channel but the channel is not available. So it blocks the current execution of the goroutine and transfers control to other goroutines, but if no other goroutine is available or other goroutines are idle due to this situation, the program will crash. This phenomenon is called deadlock. As shown in the example below:
For example:
// Chương trình Go minh hoạc
// cách deadlock phát sinh
package main
// Hàm chính
func main() {
// Tạo một kênh
// Deadlock phát sinh bởi
// không có goroutine đang viết
// vào kênh này, vì thế
// lệnh select đã bị khóa mãi mãi
c := make(chan int)
select {
case <-c: }="" }="">
Result:
fatal error: all goroutines are asleep - deadlock!
goroutine 1 [chan receive]:
main.main()
To avoid this situation, we use default case in select statement. In other words, when deadlock occurs in the program, default case of select statement is executed to avoid deadlock. As in the example below, we use default case in select statement to avoid deadlock.
For example:
// Chương trình Go minh họa cách giải quyết
// vấn đề deadlock bằng case mặc định
package main
import "fmt"
// Hàm chính
func main() {
// Tạo 1 kênh
c := make(chan int)
select {
case <-c: default:="" fmt.println("!..="" default="" case..!")="" }="" }="">
Result:
!.. Default case..!
You are also allowed to use the default case when the select statement has only nil channel . As shown in the example below, channel c is nil, so the default case is executed if the default case here is not available, then the program will block forever and deadlock arises.
For example:
// Chương trình Go minh họa
// chạy case mặc định
package main
import "fmt"
// Hàm chính
func main() {
// Tạo một kênh
var c chan int
select {
case x1 := <-c: fmt.println("value:="" ",="" x1)="" default:="" fmt.println("default="" case..!")="" }="" }="">
Result:
Default case..!
What is a Constant or Const in Golang? Here's what you need to know about using constants in Go.
Variadic functions in Go allow you to pass a variable number of arguments to a function. Here's everything you need to know about variadic functions in Golang.
In Golang, named return parameters are often referred to as named parameters. Golang allows naming the return parameters or results of functions in the function signature or definition.
Keyword - Keywords are words in a language that are used for some internal processes or represent some predefined actions. Here is what you need to know about keywords in Golang.
Data types specify what type of data a valid Go variable can hold. In the Go language, types are divided into four categories as follows:
Go supports two main ways to pass arguments: Pass by Value and Pass by Reference. Go uses pass by value by default.
In Go language, you are allowed to return multiple values from a function, using the return statement. In other words, in a function, a return statement can return multiple values.
Golang like most other programming languages has switch statement. Here is how to use switch statement in Golang.
Anonymous structs in Golang are temporary structures with no names used for one-time purposes, while anonymous fields allow embedding of unnamed fields.
What is Rune in Golang? How to use Rune in Golang? This article will give you the answer.
Operators allow us to perform different types of operations on operands. In Go language, operators can be classified based on their different functions.
_(underscore) in Golang is called Blank Identifier. Identifier is a user-defined name of program elements used for identification purposes.
Hello, World! is the first basic program in any programming language. You can write this first program in Golang by following the steps below.
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