Support parallel rm

Signed-off-by: Zhang Wei <zhangwei555@huawei.com>

command/container/utils.go

@@ -91,8 +91,8 @@ func getExitCode(dockerCli *command.DockerCli, ctx context.Context, containerID
 	return c.State.Running, c.State.ExitCode, nil
 }
 
-func parallelOperation(ctx context.Context, cids []string, op func(ctx context.Context, id string) error) chan error {
-	if len(cids) == 0 {
+func parallelOperation(ctx context.Context, containers []string, op func(ctx context.Context, container string) error) chan error {
+	if len(containers) == 0 {
 		return nil
 	}
 	const defaultParallel int = 50
@@ -101,18 +101,18 @@ func parallelOperation(ctx context.Context, cids []string, op func(ctx context.C
 
 	// make sure result is printed in correct order
 	output := map[string]chan error{}
-	for _, c := range cids {
+	for _, c := range containers {
 		output[c] = make(chan error, 1)
 	}
 	go func() {
-		for _, c := range cids {
+		for _, c := range containers {
 			err := <-output[c]
 			errChan <- err
 		}
 	}()
 
 	go func() {
-		for _, c := range cids {
+		for _, c := range containers {
 			sem <- struct{}{} // Wait for active queue sem to drain.
 			go func(container string) {
 				output[container] <- op(ctx, container)