Incorrect use of closures in Effective Go documentation #6502
Description
by shiblon:
In the Effective Go document, the following example appears in the Goroutines section:
func Serve(queue chan *Request) {
for req := range queue {
<-sem
go func() {
process(req)
sem <- 1
}()
}
}
This example is not going to work, however, because "req" gets reused at every
iteration of the loop. In order for it to be correct, it would either need "req :=
req" at the beginning of the loop body, or the request should be passed in thus:
func Serve(queue chan *Request) {
for req := range queue {
<-sem
go func(r *Request) {
process(r)
sem <- 1
}(req)
}
}
I am not sure which of the two approaches would be more idiomatic in Go (creating a new
local variable at every iteration vs. passing in a parameter), but the one that is
currently there appears incorrect.