fix Windows Service timeout during high CPU (eg. post Windows Update)

exporter.go

@@ -4,6 +4,10 @@
 package main
 
 import (
+	//Its important that we do these first so that we can register with the windows service control ASAP to avoid timeouts
+	"github.com/prometheus-community/windows_exporter/initiate"
+	"github.com/prometheus-community/windows_exporter/log"
+
 	"encoding/json"
 	"fmt"
 	"net/http"
@@ -16,12 +20,10 @@ import (
 	"sync"
 	"time"
 
-	"golang.org/x/sys/windows/svc"
-
 	"github.com/StackExchange/wmi"
 	"github.com/prometheus-community/windows_exporter/collector"
 	"github.com/prometheus-community/windows_exporter/config"
-	"github.com/prometheus-community/windows_exporter/log"
+
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/collectors"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
@@ -50,7 +52,6 @@ type prometheusVersion struct {
 const (
 	defaultCollectors            = "cpu,cs,logical_disk,net,os,service,system,textfile"
 	defaultCollectorsPlaceholder = "[defaults]"
-	serviceName                  = "windows_exporter"
 )
 
 var (
@@ -289,15 +290,14 @@ func main() {
 			"Seconds to subtract from the timeout allowed by the client. Tune to allow for overhead or high loads.",
 		).Default("0.5").Float64()
 	)
-
 	log.AddFlags(kingpin.CommandLine)
 	kingpin.Version(version.Print("windows_exporter"))
 	kingpin.HelpFlag.Short('h')
 
 	// Load values from configuration file(s). Executable flags must first be parsed, in order
 	// to load the specified file(s).
 	kingpin.Parse()
-
+	log.Debug("Logging has Started")
 	if *configFile != "" {
 		resolver, err := config.NewResolver(*configFile)
 		if err != nil {
@@ -327,21 +327,6 @@ func main() {
 
 	initWbem()
 
-	isService, err := svc.IsWindowsService()
-	if err != nil {
-		log.Fatal(err)
-	}
-
-	stopCh := make(chan bool)
-	if isService {
-		go func() {
-			err = svc.Run(serviceName, &windowsExporterService{stopCh: stopCh})
-			if err != nil {
-				log.Errorf("Failed to start service: %v", err)
-			}
-		}()
-	}
-
 	collectors, err := loadCollectors(*enabledCollectors)
 	if err != nil {
 		log.Fatalf("Couldn't load collectors: %s", err)
@@ -421,7 +406,7 @@ func main() {
 	}()
 
 	for {
-		if <-stopCh {
+		if <-initiate.StopCh {
 			log.Info("Shutting down windows_exporter")
 			break
 		}
@@ -463,33 +448,6 @@ func withConcurrencyLimit(n int, next http.HandlerFunc) http.HandlerFunc {
 	}
 }
 
-type windowsExporterService struct {
-	stopCh chan<- bool
-}
-
-func (s *windowsExporterService) Execute(args []string, r <-chan svc.ChangeRequest, changes chan<- svc.Status) (ssec bool, errno uint32) {
-	const cmdsAccepted = svc.AcceptStop | svc.AcceptShutdown
-	changes <- svc.Status{State: svc.StartPending}
-	changes <- svc.Status{State: svc.Running, Accepts: cmdsAccepted}
-loop:
-	for {
-		select {
-		case c := <-r:
-			switch c.Cmd {
-			case svc.Interrogate:
-				changes <- c.CurrentStatus
-			case svc.Stop, svc.Shutdown:
-				s.stopCh <- true
-				break loop
-			default:
-				log.Error(fmt.Sprintf("unexpected control request #%d", c))
-			}
-		}
-	}
-	changes <- svc.Status{State: svc.StopPending}
-	return
-}
-
 type metricsHandler struct {
 	timeoutMargin    float64
 	collectorFactory func(timeout time.Duration, requestedCollectors []string) (error, *windowsCollector)

initiate/initiate.go

@@ -0,0 +1,60 @@
+//This package allows us to initiate Time Sensitive components (Like registering the windows service) as early as possible in the startup process
+package initiate
+
+import (
+	"fmt"
+
+	"github.com/prometheus-community/windows_exporter/log"
+	"golang.org/x/sys/windows/svc"
+)
+
+const (
+	serviceName = "windows_exporter"
+)
+
+type windowsExporterService struct {
+	stopCh chan<- bool
+}
+
+func (s *windowsExporterService) Execute(args []string, r <-chan svc.ChangeRequest, changes chan<- svc.Status) (ssec bool, errno uint32) {
+	const cmdsAccepted = svc.AcceptStop | svc.AcceptShutdown
+	changes <- svc.Status{State: svc.StartPending}
+	changes <- svc.Status{State: svc.Running, Accepts: cmdsAccepted}
+loop:
+	for {
+		select {
+		case c := <-r:
+			switch c.Cmd {
+			case svc.Interrogate:
+				changes <- c.CurrentStatus
+			case svc.Stop, svc.Shutdown:
+				log.Debug("Service Stop Received")
+				s.stopCh <- true
+				break loop
+			default:
+				log.Error(fmt.Sprintf("unexpected control request #%d", c))
+			}
+		}
+	}
+	changes <- svc.Status{State: svc.StopPending}
+	return
+}
+
+var StopCh = make(chan bool)
+
+func init() {
+	log.Debug("Checking if We are a service")
+	isService, err := svc.IsWindowsService()
+	if err != nil {
+		log.Fatal(err)
+	}
+	log.Debug("Attempting to start exporter service")
+	if isService {
+		go func() {
+			err = svc.Run(serviceName, &windowsExporterService{stopCh: StopCh})
+			if err != nil {
+				log.Errorf("Failed to start service: %v", err)
+			}
+		}()
+	}
+}