Merge pull request #724 from crosbymichael/oom-score

Set oom score for containerd and shims

cmd/containerd/config.go

@@ -53,6 +53,8 @@ type config struct {
 	Plugins map[string]toml.Primitive `toml:"plugins"`
 	// Enable containerd as a subreaper
 	Subreaper bool `toml:"subreaper"`
+	// OOMScore adjust the containerd's oom score
+	OOMScore int `toml:"oom_score"`
 
 	md toml.MetaData
 }

cmd/containerd/main_unix.go

@@ -29,6 +29,12 @@ func platformInit(context *cli.Context) error {
 			return err
 		}
 	}
+	if conf.OOMScore != 0 {
+		log.G(global).Infof("changing OOM score to %d", conf.OOMScore)
+		if err := sys.SetOOMScore(os.Getpid(), conf.OOMScore); err != nil {
+			return err
+		}
+	}
 	return nil
 }
 

linux/shim.go

@@ -51,6 +51,9 @@ func newShim(path string, remote bool) (shim.ShimClient, error) {
 	if err := reaper.Default.Start(cmd); err != nil {
 		return nil, errors.Wrapf(err, "failed to start shim")
 	}
+	if err := sys.SetOOMScore(cmd.Process.Pid, sys.OOMScoreMaxKillable); err != nil {
+		return nil, err
+	}
 	return connectShim(socket)
 }
 

sys/oom_unix.go

@@ -0,0 +1,31 @@
+// +build !windows
+
+package sys
+
+import (
+	"fmt"
+	"os"
+	"strconv"
+
+	"github.com/opencontainers/runc/libcontainer/system"
+)
+
+// OOMScoreMaxKillable is the maximum score keeping the process killable by the oom killer
+const OOMScoreMaxKillable = -999
+
+// SetOOMScore sets the oom score for the provided pid
+func SetOOMScore(pid, score int) error {
+	path := fmt.Sprintf("/proc/%d/oom_score_adj", pid)
+	f, err := os.OpenFile(path, os.O_WRONLY, 0)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+	if _, err = f.WriteString(strconv.Itoa(score)); err != nil {
+		if os.IsPermission(err) && system.RunningInUserNS() {
+			return nil
+		}
+		return err
+	}
+	return nil
+}

sys/oom_windows.go

@@ -0,0 +1,5 @@
+package sys
+
+func SetOOMScore(pid, score int) error {
+	return nil
+}