16217: Add prometheus metrics.

[arvados.git] / services / ws / event_source.go

diff --git a/services/ws/event_source.go b/services/ws/event_source.go
index 341464de500cf784399f8df17b6d42acf4c4ebd2..60d4d40aca67ee3b504a8dba6c71def29caa1ba5 100644 (file)
--- a/services/ws/event_source.go
+++ b/services/ws/event_source.go
@@ -11,11 +11,11 @@ import (
        "fmt"
        "strconv"
        "sync"
-       "sync/atomic"
        "time"
 
        "git.arvados.org/arvados.git/sdk/go/stats"
        "github.com/lib/pq"
+       "github.com/prometheus/client_golang/prometheus"
        "github.com/sirupsen/logrus"
 )
 
@@ -24,6 +24,7 @@ type pgEventSource struct {
        MaxOpenConns int
        QueueSize    int
        Logger       logrus.FieldLogger
+       Reg          *prometheus.Registry
 
        db         *sql.DB
        pqListener *pq.Listener
@@ -32,8 +33,8 @@ type pgEventSource struct {
        mtx        sync.Mutex
 
        lastQDelay time.Duration
-       eventsIn   uint64
-       eventsOut  uint64
+       eventsIn   prometheus.Counter
+       eventsOut  prometheus.Counter
 
        cancel func()
 
@@ -41,8 +42,6 @@ type pgEventSource struct {
        ready     chan bool
 }
 
-var _ debugStatuser = (*pgEventSource)(nil)
-
 func (ps *pgEventSource) listenerProblem(et pq.ListenerEventType, err error) {
        if et == pq.ListenerEventConnected {
                ps.Logger.Debug("pgEventSource connected")
@@ -61,6 +60,90 @@ func (ps *pgEventSource) listenerProblem(et pq.ListenerEventType, err error) {
 
 func (ps *pgEventSource) setup() {
        ps.ready = make(chan bool)
+       ps.Reg.MustRegister(prometheus.NewGaugeFunc(
+               prometheus.GaugeOpts{
+                       Namespace: "arvados",
+                       Subsystem: "ws",
+                       Name:      "queue_len",
+                       Help:      "Current number of events in queue",
+               }, func() float64 { return float64(len(ps.queue)) }))
+       ps.Reg.MustRegister(prometheus.NewGaugeFunc(
+               prometheus.GaugeOpts{
+                       Namespace: "arvados",
+                       Subsystem: "ws",
+                       Name:      "queue_cap",
+                       Help:      "Event queue capacity",
+               }, func() float64 { return float64(cap(ps.queue)) }))
+       ps.Reg.MustRegister(prometheus.NewGaugeFunc(
+               prometheus.GaugeOpts{
+                       Namespace: "arvados",
+                       Subsystem: "ws",
+                       Name:      "queue_delay",
+                       Help:      "Queue delay of the last emitted event",
+               }, func() float64 { return ps.lastQDelay.Seconds() }))
+       ps.Reg.MustRegister(prometheus.NewGaugeFunc(
+               prometheus.GaugeOpts{
+                       Namespace: "arvados",
+                       Subsystem: "ws",
+                       Name:      "sinks",
+                       Help:      "Number of active sinks (connections)",
+               }, func() float64 { return float64(len(ps.sinks)) }))
+       ps.Reg.MustRegister(prometheus.NewGaugeFunc(
+               prometheus.GaugeOpts{
+                       Namespace: "arvados",
+                       Subsystem: "ws",
+                       Name:      "sinks_blocked",
+                       Help:      "Number of sinks (connections) that are busy and blocking the main event stream",
+               }, func() float64 {
+                       ps.mtx.Lock()
+                       defer ps.mtx.Unlock()
+                       blocked := 0
+                       for sink := range ps.sinks {
+                               blocked += len(sink.channel)
+                       }
+                       return float64(blocked)
+               }))
+       ps.eventsIn = prometheus.NewCounter(prometheus.CounterOpts{
+               Namespace: "arvados",
+               Subsystem: "ws",
+               Name:      "events_in",
+               Help:      "Number of events received from postgresql notify channel",
+       })
+       ps.Reg.MustRegister(ps.eventsIn)
+       ps.eventsOut = prometheus.NewCounter(prometheus.CounterOpts{
+               Namespace: "arvados",
+               Subsystem: "ws",
+               Name:      "events_out",
+               Help:      "Number of events sent to client sessions (before filtering)",
+       })
+       ps.Reg.MustRegister(ps.eventsOut)
+
+       maxConnections := prometheus.NewGauge(prometheus.GaugeOpts{
+               Namespace: "arvados",
+               Subsystem: "ws",
+               Name:      "db_max_connections",
+               Help:      "Maximum number of open connections to the database",
+       })
+       ps.Reg.MustRegister(maxConnections)
+       openConnections := prometheus.NewGaugeVec(prometheus.GaugeOpts{
+               Namespace: "arvados",
+               Subsystem: "ws",
+               Name:      "db_open_connections",
+               Help:      "Open connections to the database",
+       }, []string{"inuse"})
+       ps.Reg.MustRegister(openConnections)
+       go func() {
+               <-ps.ready
+               if ps.db == nil {
+                       return
+               }
+               for range time.Tick(time.Second) {
+                       stats := ps.db.Stats()
+                       maxConnections.Set(float64(stats.MaxOpenConnections))
+                       openConnections.WithLabelValues("0").Set(float64(stats.Idle))
+                       openConnections.WithLabelValues("1").Set(float64(stats.InUse))
+               }
+       }()
 }
 
 // Close stops listening for new events and disconnects all clients.
@@ -151,9 +234,9 @@ func (ps *pgEventSource) Run() {
                        ps.lastQDelay = e.Ready.Sub(e.Received)
 
                        ps.mtx.Lock()
-                       atomic.AddUint64(&ps.eventsOut, uint64(len(ps.sinks)))
                        for sink := range ps.sinks {
                                sink.channel <- e
+                               ps.eventsOut.Inc()
                        }
                        ps.mtx.Unlock()
                }
@@ -207,7 +290,7 @@ func (ps *pgEventSource) Run() {
                                logger:   ps.Logger,
                        }
                        ps.Logger.WithField("event", e).Debug("incoming")
-                       atomic.AddUint64(&ps.eventsIn, 1)
+                       ps.eventsIn.Inc()
                        ps.queue <- e
                        go e.Detail()
                }
@@ -258,8 +341,6 @@ func (ps *pgEventSource) DebugStatus() interface{} {
                blocked += len(sink.channel)
        }
        return map[string]interface{}{
-               "EventsIn":     atomic.LoadUint64(&ps.eventsIn),
-               "EventsOut":    atomic.LoadUint64(&ps.eventsOut),
                "Queue":        len(ps.queue),
                "QueueLimit":   cap(ps.queue),
                "QueueDelay":   stats.Duration(ps.lastQDelay),