In unbuffered channel by default sends and receives block until both the sender and receiver are ready. package main import ( "fmt" "time" ) func worker(done chan bool) { fmt.Print("working…") fmt.Println("done") done <- true } func main() { done := make(chan bool) go worker(done) time.Sleep(5 * time.Second) <-done } But the above code is executed… Read More goroutines done channel unbuffered channel
I am watching a lecture in which author build a status app using go routines which is behaving weirdly after sometime. Here’s the code: func main() { links := []string{ "http://google.com", "http://facebook.com", "http://stackoverflow.com", "http://amazon.com", "http://golang.org", } c := make(chan string) for _, link := range links { go checkLink(link, c) } for l := range… Read More Incorrect output by goroutines
So, basically, is there any difference between these 2 blocks of code? res := make(chan error, 1) go func() { res <- slowOperation() }() select { case <-time.After(deadline): return errors.New("deadline exceeded") case err := <-res: return err } and res := make(chan error, 1) select { case <-time.After(deadline): return errors.New("deadline exceeded") case res <- slowOperation():… Read More Do I have to wrap a function with goroutine to use timeout?
I’m confused as to why this code deadlocks. I’m getting a fatal error about the goroutines being asleep. I’m using a waitgroup to synchronize and wait for the goroutines to finish, as well as passing the address of the one waitgroup I created instead of copying. I tried with and without a buffer but still.… Read More Fatal Error – All Goroutines are asleep! Deadlock
In the code below, the call to io.Copy never returns; it just blocks indefinitely, causing a deadlock. This behaviour only occurs when the io.Pipe is used to connect the read io.Reader to the os.Stdout io.Writer. However, I need to use the pipe since, in my full code, I am using io.MultiWriter with io.Pipes to connect… Read More Deadlock while waiting for piped io.Copy in Goroutine
Had a hard time expressing this question in a sentence. Here is the situation: I’m trying to spawn off a set of goroutines to recurse over directories and find matching files. Then I collect those files and continue on to process them. However, the catch is that I don’t know how many files each routine… Read More How to check for goroutine completion while actively reading from channel?
Assuming that I have a function that sends web requests to an API endpoint, I would like to add a timeout to the client so that if the call is taking too long, the operation breaks either by returning an error or panicing the current thread. Another assumption is that, the client function (the function… Read More Using `Context` to implement timeout
In the below program, there is a select sequence in both C1 & C2. A deadline context for 1.5 seconds is defined in C1, which after the deadline, cancels the context, leads to ctx.Done() and prevents the reading of integers in C2 which would further cancel the context and lead to ctx.Done() in C1. If… Read More Sequence of events leading up to cancellation of context
I have case where I need to receive data on multiple channels and somehow quit infinite for loop. Here is simple example: package main import ( "fmt" "sync" "time" ) func main() { var wg sync.WaitGroup sumChannel := make(chan int) productChannel := make(chan int) for i := 1; i <= 5; i++ { wg.Add(1) go… Read More How to receive data from multiple channels using for/select syntax?
I made some edits from the gobyexample: import ( "fmt" "math/rand" "time" ) type DemoResult struct { Name string Rate int } func random(min, max int) int { rand.Seed(time.Now().UTC().UnixNano()) return rand.Intn(max-min) + min } func worker(id int, jobs <-chan int, results chan<- DemoResult) { for j := range jobs { fmt.Println("worker", id, "started job", j)… Read More How to make Go channel worker have different result's length?