Change oom metric to const

This removes the metric vec that was holding onto all task id and
namespace combinations forever, until containerd was restarted.  This
was causing a memory leak with many task.

This also removes the shim cmd where the `Args` is quite large from the
reaper after the shim has been started cutting down on another leak.

This is the first pass through the reaper but more code is required to
fix all the issues when commands are added.

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

linux/shim/client.go

@@ -49,6 +49,7 @@ func WithStart(binary, address string, debug bool) ClientOpt {
 			if err != nil {
 				terminate(cmd)
 			}
+			reaper.Default.Delete(cmd.Process.Pid)
 		}()
 		log.G(ctx).WithFields(logrus.Fields{
 			"pid":     cmd.Process.Pid,

metrics/cgroups/cgroups.go

@@ -65,6 +65,7 @@ func (m *cgroupsMonitor) Monitor(c runtime.Task) error {
 func (m *cgroupsMonitor) Stop(c runtime.Task) error {
 	info := c.Info()
 	m.collector.Remove(info.ID, info.Namespace)
+	m.oom.Remove(info.ID, info.Namespace)
 	return nil
 }
 

metrics/cgroups/oom.go

@@ -9,6 +9,7 @@ import (
 
 	"github.com/containerd/cgroups"
 	metrics "github.com/docker/go-metrics"
+	"github.com/prometheus/client_golang/prometheus"
 	"github.com/sirupsen/logrus"
 )
 
@@ -19,19 +20,20 @@ func NewOOMCollector(ns *metrics.Namespace) (*OOMCollector, error) {
 	}
 	c := &OOMCollector{
 		fd:   fd,
-		memoryOOM: ns.NewLabeledGauge("memory_oom", "The number of times a container received an oom event", metrics.Total, "container_id", "namespace"),
 		set:  make(map[uintptr]*oom),
+		desc: ns.NewDesc("memory_oom", "The number of times a container has received an oom event", metrics.Total, "container_id", "namespace"),
 	}
 	go c.start()
+	ns.Add(c)
 	return c, nil
 }
 
 type OOMCollector struct {
 	mu sync.Mutex
 
-	memoryOOM metrics.LabeledGauge
 	fd   int
 	set  map[uintptr]*oom
+	desc *prometheus.Desc
 }
 
 type oom struct {
@@ -39,6 +41,7 @@ type oom struct {
 	namespace string
 	c         cgroups.Cgroup
 	triggers  []Trigger
+	count     int
 }
 
 func (o *OOMCollector) Add(id, namespace string, cg cgroups.Cgroup, triggers ...Trigger) error {
@@ -50,12 +53,10 @@ func (o *OOMCollector) Add(id, namespace string, cg cgroups.Cgroup, triggers ...
 	}
 	o.set[fd] = &oom{
 		id:        id,
+		namespace: namespace,
 		c:         cg,
 		triggers:  triggers,
-		namespace: namespace,
 	}
-	// set the gauge's default value
-	o.memoryOOM.WithValues(id, namespace).Set(0)
 	event := unix.EpollEvent{
 		Fd:     int32(fd),
 		Events: unix.EPOLLHUP | unix.EPOLLIN | unix.EPOLLERR,
@@ -66,11 +67,37 @@ func (o *OOMCollector) Add(id, namespace string, cg cgroups.Cgroup, triggers ...
 	return nil
 }
 
+func (o *OOMCollector) Remove(id, namespace string) {
+	o.mu.Lock()
+	defer o.mu.Unlock()
+	for fd, t := range o.set {
+		if t.id == id && t.namespace == namespace {
+			unix.Close(int(fd))
+			delete(o.set, fd)
+			return
+		}
+	}
+}
+
 // Close closes the epoll fd
 func (o *OOMCollector) Close() error {
 	return unix.Close(int(o.fd))
 }
 
+func (o *OOMCollector) Describe(ch chan<- *prometheus.Desc) {
+	o.mu.Lock()
+	defer o.mu.Unlock()
+	ch <- o.desc
+}
+
+func (o *OOMCollector) Collect(ch chan<- prometheus.Metric) {
+	o.mu.Lock()
+	defer o.mu.Unlock()
+	for _, t := range o.set {
+		ch <- prometheus.MustNewConstMetric(o.desc, prometheus.GaugeValue, float64(t.count), t.id, t.namespace)
+	}
+}
+
 func (o *OOMCollector) start() {
 	var events [128]unix.EpollEvent
 	for {
@@ -107,7 +134,7 @@ func (o *OOMCollector) process(fd uintptr, event uint32) {
 		unix.Close(int(fd))
 		return
 	}
-	o.memoryOOM.WithValues(info.id, info.namespace).Inc(1)
+	info.count++
 	for _, t := range info.triggers {
 		t(info.id, info.c)
 	}

runtime/task.go

@@ -9,7 +9,6 @@ import (
 type TaskInfo struct {
 	ID        string
 	Runtime   string
-	Spec      []byte
 	Namespace string
 }