Pro Exceptionally simple and scalable multithreaded and concurrent programming Goroutines are "lightweight threads" that runs on OS threads. They provide a simple way for concurrent operations — prepending a function with go will execute it concurrently. It utilizes channels for communication between goroutines which aids to prevent races and makes synchronizing execution effortless across goroutines.
Concurrency seems to be the big buzz word around the language. It was for me when I first started hearing about Go. To understand how Go makes writing concurrent programs easier and less prone to errors, we first need to understand what a concurrent program is and the problems that result from such programs.
This post will focus on what a concurrent program is, the role that goroutines play and how the GOMAXPROCS environment variable and runtime function affects the behavior of the Go runtime and the programs we write.
Processes and Threads When we run an application, like the browser I am using to write this post, a process is created by the operating system for the application. The job of the process is to act like a container for all the resources the application uses and maintains as it runs.
These resources include things like a memory address space, handles to files, devices and threads. A thread is a path of execution that is scheduled by the operating system to execute the code we write in our functions against a processor.
A process starts out with one thread, the main thread, and when that thread terminates the process terminates. This is because the main thread is the origin for the application. The main thread can then in turn launch more threads and those threads can launch even more threads.
The operating system schedules a thread to run on an available processor regardless of which process the thread belongs to. Each operating system has its own algorithms that make these decisions and it is best for us to write concurrent programs that are not specific to one algorithm or the other.
Plus these algorithms change with every new release of an operating system, so it is dangerous game to play.
Goroutines and Parallelism Any function or method in Go can be created as a goroutine. Goroutines are considered to be lightweight because they use little memory and resources plus their initial stack size is small. Prior to version 1.
The stack has the ability to grow as needed. By default, the Go runtime allocates a single logical processor to execute all the goroutines that are created for our program.
Even with this single logical processor and operating system thread, hundreds of thousands of goroutines can be scheduled to run concurrently with amazing efficiency and performance. It is not recommended to add more that one logical processor, but if you want to run goroutines in parallel, Go provides the ability to add more via the GOMAXPROCS environment variable or runtime function.
Concurrency is not Parallelism. Parallelism is when two or more threads are executing code simultaneously against different processors. If you configure the runtime to use more than one logical processor, the scheduler will distribute goroutines between these logical processors which will result in goroutines running on different operating system threads.
However, to have true parallelism you need to run your program on a machine with multiple physical processors. If not, then the goroutines will be running concurrently against a single physical processor, even though the Go runtime is using multiple logical processors.
In this example we are running the code with one logical processor:are operating system speciﬁc software and function as an interface in between a physical device also called Golang, is a statically typed, compiled and imperative programming information are channels instead of sharing memory in order to further simplify con-.
Passing Data between Go Routines with Channels Aug 6, · words · 1 minute read #goroutine #channel #chan #concurrency #parallelism #data #make Go, as a language, makes it very easy to work in parallel on data through it use of go routines (more info on go routines here).
Channels of channels One of the most important properties of Go is that a channel is a first-class value that can be allocated and passed around like any other. A common use of this property is to implement safe, parallel demultiplexing.
The Go runtime will schedule the goroutines, similar to an operating scheduling threads. A Go proverb says: Share memory by communicating.
You can share a value between concurrent parts of you program by sending and receiving on channels. The Go runtime uses non-blocking I/O syscalls to avoid the operating system blocking the thread so a different goroutine can be run on it while the first is waiting for it's I/O.
Goroutines are really cheap so writing non-blocking style code is not needed. Go (often referred to as Golang) is a programming language created by Google in by Robert Griesemer, Rob Pike, and Ken Thompson. Go is a statically typed, compiled language in the tradition of C, with memory safety, garbage collection, structural typing, and CSP-style concurrency.