benchmarking - Benchmark Go code and goroutines -

i benchmark function: test(), different numbers of threads working on it.

without goroutines:

var t1 = time.now() test() var elapsed1 = time.since(t1) 

1 ns / operation

with goroutines:

runtime.gomaxprocs(1) var t1 = time.now() go test() var elapsed1 = time.since(t1) 

1.10^-6 ns / operation

my test function:

func test() {     := 0; < 1000000000; i++ {         float_result = f1 + f2         float_result = f1 - f2         float_result = f1 * f2         float_result = f1 / f2         float_result = f1 + f2         float_result = f1 - f2         float_result = f1 * f2         float_result = f1 / f2         float_result = f1 + f2         float_result = f1 - f2         float_result = f1 * f2         float_result = f1 / f2         float_result = f1 + f2         float_result = f1 - f2         float_result = f1 * f2         float_result = f1 / f2         float_result = f1 + f2         float_result = f1 - f2         float_result = f1 * f2         float_result = f1 / f2     } } 

• is test() function benchmarked when use goroutines in case?
• how possible reach 0.001ns / operation? looks way fast. (2.5ghz intel core i7)
• is use of goroutines runtime.gomaxprocs(n) equivalent use n threads ?

you not measuring time test() runs, time takes call/create new goroutine go test().

you need wait goroutine(s) finish, example using sync.waitgroup.

// somewhere in main package var wg sync.waitgroup  func test() {    // first lines in test() should    wg.add(1)    defer wg.done()    ... }   // benchmark runtime.gomaxprocs(1) var t1 = time.now() go test() wg.wait() var elapsed1 = time.since(t1)