add initial queue to runner

api/runner/runner.go

@@ -1,12 +1,19 @@
 package runner
 
 import (
+	"bufio"
+	"errors"
 	"fmt"
 	"io"
+	"io/ioutil"
+	"os"
+	"strconv"
+	"strings"
 	"time"
 
 	"golang.org/x/net/context"
 
+	"github.com/Sirupsen/logrus"
 	"github.com/iron-io/titan/common"
 	"github.com/iron-io/titan/runner/agent"
 	"github.com/iron-io/titan/runner/drivers"
@@ -20,15 +27,24 @@ type Config struct {
 	Image   string
 	Timeout time.Duration
 	AppName string
+	Memory  uint64
 	Env     map[string]string
 	Stdout  io.Writer
 	Stderr  io.Writer
 }
 
 type Runner struct {
-	driver drivers.Driver
+	driver    drivers.Driver
+	taskQueue chan *containerTask
 }
 
+var (
+	ErrTimeOutNoMemory = errors.New("Task timed out. No available memory.")
+	ErrFullQueue       = errors.New("The runner queue is full")
+
+	WaitMemoryTimeout = 3 * time.Second
+)
+
 func New() (*Runner, error) {
 	// TODO: Is this really required for Titan's driver?
 	// Can we remove it?
@@ -40,30 +56,107 @@ func New() (*Runner, error) {
 		return nil, err
 	}
 
-	return &Runner{
-		driver: driver,
-	}, nil
+	r := &Runner{
+		driver:    driver,
+		taskQueue: make(chan *containerTask, 0),
+	}
+
+	go r.queueHandler()
+
+	return r, nil
+}
+
+// This routine checks for available memory;
+// If there's memory then send signal to the task to proceed.
+// If there's not available memory to run the task it waits
+// If the task waits for more than X seconds it timeouts
+func (r *Runner) queueHandler() {
+	var task *containerTask
+	var waitStart time.Time
+	var waitTime time.Duration
+	var timedOut bool
+	for {
+		select {
+		case task = <-r.taskQueue:
+			waitStart = time.Now()
+			timedOut = false
+		}
+
+		// Loop waiting for available memory
+		avail := dynamicSizing(task.cfg.Memory)
+		for ; avail == 0; avail = dynamicSizing(task.cfg.Memory) {
+			waitTime = time.Since(waitStart)
+			if waitTime > WaitMemoryTimeout {
+				timedOut = true
+				break
+			}
+		}
+
+		metricBaseName := fmt.Sprintf("run.%s.", task.cfg.AppName)
+		LogMetricTime(task.ctx, (metricBaseName + "waittime"), waitTime)
+
+		if timedOut {
+			// Send to a signal to this task saying it cannot run
+			task.canRun <- false
+			continue
+		}
+
+		// Send a signal to this task saying it can run
+		task.canRun <- true
+	}
 }
 
 func (r *Runner) Run(ctx context.Context, cfg *Config) (drivers.RunResult, error) {
 	var err error
 
 	ctask := &containerTask{
-		cfg:  cfg,
-		auth: &agent.ConfigAuth{},
+		ctx:    ctx,
+		cfg:    cfg,
+		auth:   &agent.ConfigAuth{},
+		canRun: make(chan bool),
 	}
 
+	metricBaseName := fmt.Sprintf("run.%s.", cfg.AppName)
+	LogMetricCount(ctx, (metricBaseName + "requests"), 1)
+
 	closer, err := r.driver.Prepare(ctx, ctask)
 	if err != nil {
 		return nil, err
 	}
 	defer closer.Close()
 
+	// Check if has enough available memory
+	if dynamicSizing(cfg.Memory) == 0 {
+		// If not, try add task to the queue
+		select {
+		case r.taskQueue <- ctask:
+		default:
+			// If queue is full, return error
+			return nil, ErrFullQueue
+		}
+
+		// If task was added to the queue, wait for permission
+		if ok := <-ctask.canRun; !ok {
+			// This task timed out, not available memory
+			return nil, ErrTimeOutNoMemory
+		}
+	}
+
+	metricStart := time.Now()
 	result, err := r.driver.Run(ctx, ctask)
 	if err != nil {
 		return nil, err
 	}
 
+	if result.Status() == "success" {
+		LogMetricCount(ctx, (metricBaseName + "succeeded"), 1)
+	} else {
+		LogMetricCount(ctx, (metricBaseName + "error"), 1)
+	}
+
+	metricElapsed := time.Since(metricStart)
+	LogMetricTime(ctx, (metricBaseName + "time"), metricElapsed)
+
 	return result, nil
 }
 
@@ -90,3 +183,77 @@ func selectDriver(driver string, env *common.Environment, conf *driverscommon.Co
 	}
 	return nil, fmt.Errorf("driver %v not found", driver)
 }
+
+func dynamicSizing(reqMem uint64) int {
+	const tooBig = 322122547200 // #300GB or 0, biggest aws instance is 244GB
+
+	availableMemory, err := checkCgroup()
+	if err != nil {
+		logrus.WithError(err).Error("Error checking for cgroup memory limits, falling back to host memory available..")
+	}
+	if availableMemory > tooBig || availableMemory == 0 {
+		// Then -m flag probably wasn't set, so use max available on system
+		availableMemory, err = checkProc()
+		if availableMemory > tooBig || availableMemory == 0 {
+			logrus.WithError(err).Fatal("Your Linux version is too old (<3.14) then we can't get the proper information to . You must specify the maximum available memory by passing the -m command with docker run when starting the runner via docker, eg:  `docker run -m 2G ...`")
+		}
+	}
+
+	c := availableMemory / (reqMem * 1024 * 1024)
+
+	return int(c)
+}
+
+func checkCgroup() (uint64, error) {
+	f, err := os.Open("/sys/fs/cgroup/memory/memory.limit_in_bytes")
+	if err != nil {
+		return 0, err
+	}
+	defer f.Close()
+	b, err := ioutil.ReadAll(f)
+	limBytes := string(b)
+	limBytes = strings.TrimSpace(limBytes)
+	if err != nil {
+		return 0, err
+	}
+	return strconv.ParseUint(limBytes, 10, 64)
+}
+
+func checkProc() (uint64, error) {
+	f, err := os.Open("/proc/meminfo")
+	if err != nil {
+		return 0, err
+	}
+	defer f.Close()
+
+	scanner := bufio.NewScanner(f)
+	for scanner.Scan() {
+		b := scanner.Text()
+		if !strings.HasPrefix(b, "MemFree") {
+			continue
+		}
+
+		// expect form:
+		// MemAvailable: 1234567890 kB
+		tri := strings.Fields(b)
+		if len(tri) != 3 {
+			return 0, fmt.Errorf("MemAvailable line has unexpected format: %v", b)
+		}
+
+		c, err := strconv.ParseUint(tri[1], 10, 64)
+		if err != nil {
+			return 0, fmt.Errorf("Could not parse MemAvailable: %v", b)
+		}
+		switch tri[2] { // convert units to bytes
+		case "kB":
+			c *= 1024
+		case "MB":
+			c *= 1024 * 1024
+		default:
+			return 0, fmt.Errorf("Unexpected units for MemAvailable in /proc/meminfo, need kB or MB, got: %v", tri[2])
+		}
+		return c, nil
+	}
+
+	return 0, fmt.Errorf("Didn't find MemAvailable in /proc/meminfo, kernel is probably < 3.14")
+}

api/runner/task.go

@@ -3,14 +3,18 @@ package runner
 import (
 	"io"
 
+	"golang.org/x/net/context"
+
 	dockercli "github.com/fsouza/go-dockerclient"
 	"github.com/iron-io/titan/runner/drivers"
 	"github.com/iron-io/titan/runner/tasker"
 )
 
 type containerTask struct {
-	auth tasker.Auther
-	cfg  *Config
+	ctx    context.Context
+	auth   tasker.Auther
+	cfg    *Config
+	canRun chan bool
 }
 
 func (t *containerTask) Command() string { return "" }

api/server/runner.go

@@ -108,10 +108,6 @@ func handleRunner(c *gin.Context) {
 		log = log.WithFields(logrus.Fields{
 			"app": appName, "route": el.Path, "image": el.Image, "request_id": reqID})
 
-		// Request count metric
-		metricBaseName := "server.handleRunner." + appName + "."
-		runner.LogMetricCount(ctx, (metricBaseName + "requests"), 1)
-
 		if params, match := matchRoute(el.Path, route); match {
 
 			var stdout bytes.Buffer // TODO: should limit the size of this, error if gets too big. akin to: https://golang.org/pkg/io/#LimitReader
@@ -152,9 +148,9 @@ func handleRunner(c *gin.Context) {
 				Stdout:  &stdout,
 				Stderr:  stderr,
 				Env:     envVars,
+				Memory:  el.Memory,
 			}
 
-			metricStart := time.Now()
 			if result, err := Api.Runner.Run(c, cfg); err != nil {
 				log.WithError(err).Error(models.ErrRunnerRunRoute)
 				c.JSON(http.StatusInternalServerError, simpleError(models.ErrRunnerRunRoute))
@@ -165,19 +161,11 @@ func handleRunner(c *gin.Context) {
 
 				if result.Status() == "success" {
 					c.Data(http.StatusOK, "", stdout.Bytes())
-					runner.LogMetricCount(ctx, (metricBaseName + "succeeded"), 1)
-
 				} else {
-					// log.WithFields(logrus.Fields{"app": appName, "route": el, "req_id": reqID}).Debug(stderr.String())
-					// Error count metric
-					runner.LogMetricCount(ctx, (metricBaseName + "error"), 1)
 
 					c.AbortWithStatus(http.StatusInternalServerError)
 				}
 			}
-			// Execution time metric
-			metricElapsed := time.Since(metricStart)
-			runner.LogMetricTime(ctx, (metricBaseName + "time"), metricElapsed)
 			return
 		}
 	}