Unlike C/C++, Go has GC, so we don’t need to handle memory allocation/release. However, we also should be cautious about memory leak.
Today, let’s see a memory leak case caused by slice .
package mainimport (
"fmt"
)type Object struct {}func main() {
var a []*Object
for i := 0; i < 8; i++ {
a = append(a, new(Object))
} fmt.Println(cap(a), len(a)) // Output: 8, 8 a = remove(a, 5) fmt.Println(cap(a), len(a)) // Output: 8, 7
}func remove(s []*Object, i int) []*Object {
return append(s[:i], s[i+1:]...)
}
Click https://play.golang.org/p/BxybSc5PDfF to run the example. We can notice the capacity of a is still 8 even one object has been removed, which means function remove may cause a potential memory leak.
Why would it happen?
As we know, every slice has an underlying array, an array may be shared among several slices. If the new slice’s length will exceed the array’s capacity, a new array will be created for the new slice. Usually new capacity will be two times old capacity. In another word, we can think slice is a view of the part array, just like the relationship between view and table in database.
Let’s take a look at an example
package mainimport (
"fmt"
)
