code block in goroutine produces strange wrong results

i have a big N*1 name array
i am currently using goroutine to calculate the edit distance of a name among each other

the question is the results at [B] [C] are different, maybe like

ABC BCD 7
ABC BCD 3

there are 20000 records in names

var names []string

divide names into two chunks

nameCount := len(names)  
procs := 2  
chunkSize := nameCount / procs 

channel

ch := make(chan int)  
var wg sync.WaitGroup


for i := 0; i < procs; i++ { //create two goroutines
	start := i * chunkSize
	end := (i+1)*chunkSize - 1
	fmt.Println(start, end) //get slice start and end
	wg.Add(1)
	go func(slices []string, allnames []string) {
		for _, slice := range slices {
			minDistance = 256
			distance := 0
			sum := 0
			for _, name := range allnames {
				distance = calcEditDist(slice, name) //get the LD [A]
				sum += 1
				if distance > 0 && distance < minDistance {
					minDistance = distance
					fmt.Println(slice, name, distance) //[B]
					fmt.Println(slice, name, calcEditDist(slice, name)) //[C]
				} else if distance == minDistance {
					fmt.Println(slice, name, distance)
					fmt.Println(slice, name, calcEditDist(slice, name))
				}
			}
			// for _, name := range allnames {
			// 	fmt.Println(slice, name)
			// }
			ch <- sum
			// fmt.Println(len(allnames), slice)
			break
		}
		wg.Done()
	}(names[start:end], names)
}

i placed the calcEditDist @https://github.com/copywrite/keyboardDistance/blob/master/parallel.go

PS:
if i declare

var dp [max][max]int

in calcEditDist as local variable instead of global, the results are right, but is incredibly slow

UPDATE 1
Thanks all buddy,i take the great advice below in three steps

1. i shrinked the dp to a much reasonable size, like 100 or even smaller, DONE
2. i put the dp declaration in each goroutine and pass its pointer as Nick said, DONE
3. later i will try to dynamically alloc dp, LATER

the performance improved steeply, ╰(°▽°)╯

As you've identified in your posting, having dp as a global variable is the problem.

Allocating it each time in CalcEditDistance is too slow.

You have two possible solutions.

1. you only need 1 dp array per go-routine, so allocate it in the for loop loop and pass a pointer to it (don't pass the array directly as arrays pass by value which will involve a lot of copying!)

   for i := 0; i < procs; i++ { //create two goroutines
   start := i * chunkSize
   end := (i+1)*chunkSize - 1
   fmt.Println(start, end) //get slice start and end
   wg.Add(1)
   go func(slices []string, allnames []string) {
   var dp [max][max]int // allocate
   for _, slice := range slices {
   minDistance = 256
   distance := 0
   sum := 0
   for _, name := range allnames {
   distance = calcEditDist(slice, name, &dp) // pass dp pointer here

Change calcEditDist to take the dp

func CalcEditDist(A string, B string, dp *[max][max]int) int {
        lenA := len(A)
        lenB := len(B)

2. Re-write your calcEditDistance so it doesn't need the massive O(N^2) dp array.

If you study the function carefully it only ever accesses a row up and a column to the left, so all the storage you actually need is a previous row and a previous columns which you could allocate dynamically at very little cost. This would make it scale to any length of string too.

That would need a bit of careful thought though!