Method ListContainerStats

core/stats.go:190–266

ListContainerStats returns stats for a list container stats request based on a filter.

(
	ctx context.Context,
	r *runtimeapi.ListContainerStatsRequest,
)

// ListContainerStats returns stats for a list container stats request based on a filter.
func (ds *dockerService) ListContainerStats(
	ctx context.Context,
	r *runtimeapi.ListContainerStatsRequest,
) (*runtimeapi.ListContainerStatsResponse, error) {
	start := time.Now()
	containerStatsFilter := r.GetFilter()
	filter := &runtimeapi.ContainerFilter{}

	if containerStatsFilter != nil {
		filter.Id = containerStatsFilter.Id
		filter.PodSandboxId = containerStatsFilter.PodSandboxId
		filter.LabelSelector = containerStatsFilter.LabelSelector
	}

	res, err := ds.ListContainers(ctx, &runtimeapi.ListContainersRequest{Filter: filter})
	if err != nil {
		logrus.Errorf("Error listing containers with filter: %+v", filter)
		logrus.Errorf("Error listing containers error: %s", err)
		return nil, err
	}
	containers := res.Containers
	ds.containerStatsCache.clist <- containers
	numContainers := len(containers)
	logrus.Debugf("Number of pod containers: %v", numContainers)
	if numContainers == 0 {
		return &runtimeapi.ListContainerStatsResponse{}, nil
	}

	var mu sync.Mutex
	results := make([]*runtimeapi.ContainerStats, 0, len(containers))

	g, ctx := errgroup.WithContext(ctx)
	// The `getContainerStats` may take some time. When there are many containers,
	// the whole `ListContainerStats` may have long delays if the number of workers is
	// small. So we want to set a bigger value for the number of workers to avoid
	// too long delays before the issue mentioned in https://github.com/moby/moby/pull/46448
	// is fixed.
	// Consider a common node with 8 CPU running dozens of pods, NumCPU() * 6 may be a moderate
	// number.
	numWorkers := runtime.NumCPU() * 6
	if numWorkers > numContainers {
		numWorkers = numContainers
	}
	g.SetLimit(numWorkers)

	// Collect container stats and send to result channel.
	// The concurrency is numWorkers
	for _, c := range containers {
		c := c
		g.Go(func() error {
			if ctx.Err() != nil {
				return ctx.Err()
			}
			stats, err := ds.getContainerStats(c)
			if err != nil {
				logrus.Errorf("error collecting stats for container '%s': %v", c.Metadata.Name, err)
				return nil
			}