Possibly undesired value being used in goroutine RVV-B0007
Bug risk
Major
6 months ago
—
a year old
loop variable nth captured by func literal
88 }
89 }()
90
91 logname := fmt.Sprintf("/tmp/%s-%d.log", c.GetID(), nth) 92 logfile, err := os.Create(logname)
93 if err == nil {
94 defer func() {
Description
Range variables in a loop are reused at each iteration; therefore a goroutine created in a loop will point to the range variable with from the upper scope. This way, the goroutine could use the variable with an undesired value. This rule warns when a range value (or index) is used inside a closure.
Bad practice
mySlice := []string{"A", "B", "C"}
for index, value := range mySlice {
go func() {
fmt.Printf("Index: %d\n", index)
fmt.Printf("Value: %s\n", value)
}()
}
Recommended
mySlice := []string{"A", "B", "C"}
for index, value := range mySlice {
index := index
value := value
go func() {
fmt.Printf("Index: %d\n", index)
fmt.Printf("Value: %s\n", value)
}()
}