Possible data race in manager memory test

[VincentRbbmnd]

Found in manager/state/store/memory_test.go lines 2036-2054

for c := 0; c != 5; c++ {
	wg.Add(1)
	go func() {
		defer wg.Done()
		for i := 0; i < b.N; i++ {
			_ = s.Update(func(tx1 Tx) error {
				_ = UpdateNode(tx1, &api.Node{
					ID: nodeIDs[i%benchmarkNumNodes],
					Spec: api.NodeSpec{
						Annotations: api.Annotations{
							Name: nodeIDs[i%benchmarkNumNodes] + "_" + strconv.Itoa(c) + "_" + strconv.Itoa(i),
						},
					},
				})
				return nil
			})
		}
	}()
}

Loop variable c is used within the func literal (in the statement strconv.Itoa(c)), possibly leading to a data race, causing all loop iterations to use the same value of c as mentioned here.

Two possible fixes:

• Pass c as a param in the func literal

  go func(c int) {
      ...
  }(c)

• Create a new variable

  for c := 0; c != 5; c++ {
      ...
      x := c
      go func() {
          ...
          Name: nodeIDs[i%benchmarkNumNodes] + "_" + strconv.Itoa(x) + "_" + strconv.Itoa(i),
          ...
      }
  }

[nishanttotla]

This was fixed in #2537.