Hi, As a fun way of getting into Go I decided to create a "random" number generator by timing a number of requests to a specific URL, and reducing the results to one number. For practice pusposes I made a "naive" version with just a for loop and a version that uses goroutines. As I am interested in the timings for each individual request, there was an interesting result. Implemented in the for loop, each request was timed as expected. For the goroutines however the timings incremented for each individual timing, where the last timing was equal or a microsecond or so below the total timing for all requests. Upon further inspection, it seems that the time.Now() for the startTime is called almost immediately for all, but the time.Now() for the stopSub is called much later. How is it possible that all goroutines start execution at the same time, but finish not at the same time? Is there maybe something blocking involved in http.Get()? I posted all code for this on Stackoverflow a couple of days ago but no answers there yet (go - Unexpected behaviour of time.Now() in goroutine - Stack Overflow <https://stackoverflow.com/questions/71737286/unexpected-behaviour-of-time-now-in-goroutine>). See below for the goroutine and how it is called.
Execution of goroutines: *start := time.Now()* * ch := make(chan int64, 100)* * url := "https://www.nu.nl"* * for i := 0; i < len(timings_parallel); i++ {* * wg.Add(1)* * go func() {* * defer wg.Done()* * doGet(url, ch)* * }()* * }* * wg.Wait()* * close(ch)* * // feed the results from the channel into the result array* * count := 0* * for ret := range ch {* * timings_parallel[count] = ret* * count++* * }* * // get total running time for this part* * time_parallel := time.Since(start).Milliseconds()* Goroutine: *func doGet(address string, channel chan int64) {* * startTime := time.Now()* * startSub := startTime.UnixMilli()* * _, err := http.Get(address)* * if err != nil {* * log.Fatalln(err)* * }* * stopSub := time.Now().UnixMilli()* * delta := stopSub - startSub* * channel <- delta* *}* -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/9a4896fd-5e92-4462-9e6a-7363aa19a483n%40googlegroups.com.
