chore: debounce agent watch-metadata stream (#6940)

coderd/workspaceagents.go

@@ -6,6 +6,7 @@ import (
 	"database/sql"
 	"encoding/json"
 	"errors"
+	"flag"
 	"fmt"
 	"net"
 	"net/http"
@@ -18,6 +19,7 @@ import (
 	"sync/atomic"
 	"time"
 
+	"github.com/bep/debounce"
 	"github.com/go-chi/chi/v5"
 	"github.com/google/uuid"
 	"go.opentelemetry.io/otel/trace"
@@ -1484,9 +1486,18 @@ func (api *API) watchWorkspaceAgentMetadata(rw http.ResponseWriter, r *http.Requ
 	// Send initial metadata.
 	sendMetadata(true)
 
+	// We debounce metadata updates to avoid overloading the frontend when
+	// an agent is sending a lot of updates.
+	pubsubDebounce := debounce.New(time.Second)
+	if flag.Lookup("test.v") != nil {
+		pubsubDebounce = debounce.New(time.Millisecond * 100)
+	}
+
 	// Send metadata on updates.
 	cancelSub, err := api.Pubsub.Subscribe(watchWorkspaceAgentMetadataChannel(workspaceAgent.ID), func(_ context.Context, _ []byte) {
-		sendMetadata(true)
+		pubsubDebounce(func() {
+			sendMetadata(true)
+		})
 	})
 	if err != nil {
 		httpapi.InternalServerError(rw, err)

go.mod

@@ -173,6 +173,7 @@ require (
 
 require (
 	cloud.google.com/go/logging v1.6.1 // indirect
+	github.com/bep/debounce v1.2.1 // indirect
 	github.com/dgraph-io/badger/v3 v3.2103.5 // indirect
 	github.com/dustin/go-humanize v1.0.1 // indirect
 	github.com/golang/glog v1.0.0 // indirect

go.sum

@@ -270,6 +270,8 @@ github.com/beorn7/perks v0.0.0-20180321164747-3a771d992973/go.mod h1:Dwedo/Wpr24
 github.com/beorn7/perks v1.0.0/go.mod h1:KWe93zE9D1o94FZ5RNwFwVgaQK1VOXiVxmqh+CedLV8=
 github.com/beorn7/perks v1.0.1 h1:VlbKKnNfV8bJzeqoa4cOKqO6bYr3WgKZxO8Z16+hsOM=
 github.com/beorn7/perks v1.0.1/go.mod h1:G2ZrVWU2WbWT9wwq4/hrbKbnv/1ERSJQ0ibhJ6rlkpw=
+github.com/bep/debounce v1.2.1 h1:v67fRdBA9UQu2NhLFXrSg0Brw7CexQekrBwDMM8bzeY=
+github.com/bep/debounce v1.2.1/go.mod h1:H8yggRPQKLUhUoqrJC1bO2xNya7vanpDl7xR3ISbCJ0=
 github.com/bep/godartsass v0.16.0 h1:nTpenrZBQjVSjLkCw3AgnYmBB2czauTJa4BLLv448qg=
 github.com/bep/godartsass v0.16.0/go.mod h1:6LvK9RftsXMxGfsA0LDV12AGc4Jylnu6NgHL+Q5/pE8=
 github.com/bep/golibsass v1.1.0 h1:pjtXr00IJZZaOdfryNa9wARTB3Q0BmxC3/V1KNcgyTw=