To run a GoLang program, there needs to be a main() function defined. In some cases when developing some demo program which has multiple files and just wanna put them in the same main package and this folder is not in GOPATH, how to run the program?Let's say we have following folder structure where the main() function is defined in main.go.If you just run below command, it would fail to start to run the program and gives some error if some struct is defined in other files and being used.PS D:\Project\Go\sourcecode_updater\v2> go run main.go# command-line-arguments.\main.go:35:11: undefined:...

If goroutine and channel are considered as the foundation for GoLang concurrency, interface would be the key for data types in GoLang. In practical Go programming, almost all data types are built/used around interfaces, interface is the core of GoLang data structures.Go is not a typical OOP language, it has no class and inheritance concept syntactically. But it doesn't mean that there cannot be polymorphism in GoLang. Because of interface, it achieves the same polymorphism effect as in C++, though syntactically different.Although Go doesn't have concept of class, it allows different data types...

Error handling is one of the must talked topics for any programming language. The program would be more reliable and stable if errors are handled properly and timely. Each programming language has its own way to handle error, this applies to GoLang as well. This post will discuss more about GoLang's error handling mechanism.Error handlingBefore talking more about GoLang's error handling, we can see how different programming languages are handling errors.C's error checkThe most direct way of checking error is using error code, and this is also how error is being checked traditionally. In proced...

Note: The post is authorized by original author to republish on our site. Original author is Stefanie Lai who is currently a Spotify engineer and lives in Stockholm, original post is published here.Last week, Go1.16 was released, bringing relatively more changes than version 1.15, which was influenced by the epidemic.The update is in many aspects, including compilation, deployment, standard library, etc. In the official Go document, all changes are classified based on Tools, Runtime, Complier, etc.It is undoubtedly good to dig into all the changes, but sometimes we understa...

Normally people would not pay much attention to which GoLang version is being used as lots of functions are backward compatible. However there are cases where GoLang version does matter as some functions may not be supported by old version of GoLang. For example, strings.Builder is introduced in Go 1.10, but below code would fail to be compiled on Go 1.10.package mainimport ( "fmt" "strings")func main() { var b strings.Builder b.WriteString("polarisxu") fmt.Println(b.Cap())}The compilation error is:$ go versiongo version go1.10.8 darwin/amd64$ go run main.go# command-line-arguments./main.g...

gRPC is a RPC framework based on HTTP and is frequently used for communications among micro service inside the same organization network. However,  the service functions cannot be accessed via normal HTTP URL as it's not a WEB framework. In this case, how to do pprof on a gRPC service?The trick is starting a HTTP server asynchronously while starting the gRPC service. This HTTP server can be accessed to run prrof debug.go func(){ http.ListenAndServe(":10001", nil)}()Since it uses the default ServerMux, the pprof related routes will be registered automatically after importing the package&nb...

A worker pool is a pool where a specified number of workers(usually goroutine) created and run to pick up tasks. This can allow multiple tasks to be ran at the same time while keeping the number of workers a fixed number to avoid overuse of resource in the program.There are usually two approaches of creating worker pool.One is with fixed number of workers pre-createdOne is creating worker when needed until the max number of workers createdIn this post, we will cover the demonstration of creating fixed number of workers pre-ahead. This approach is usually used when one knows there are lots of t...

When running lscpu command on Linux, it will list the CPU info on the machine. Take one example where there is one CPU with 2 cores and each core has two threads which indicates there are 4 cores available.Now let's see how many cores GoLang program would identify.From output, NumCPU and GOMAXPROCS both output 4 which is expected. How does go runtime get this info, does it get it through similar command like lscpu or /proc/cpuinfo? Let's dig more in GoLang's source code.In runtime/debug.go, it tells that this value is from the global variable ncpu which is set when process starts and...