From da7bca0224760a4fe0e10876a9c11da333513a29 Mon Sep 17 00:00:00 2001
From: Till <2353100+S7evinK@users.noreply.github.com>
Date: Tue, 31 Oct 2023 16:39:45 +0100
Subject: [PATCH] Some tweaks for the device list updater (#3251)

This makes the following changes:
- Adds two new metrics observing the usage of the `DeviceListUpdater`
workers
- Makes the number of workers configurable
- Adds a 30s timeout for DB requests when receiving a device list update
over federation
---
 appservice/appservice_test.go                 |  6 ++--
 build/dendritejs-pinecone/main.go             |  3 +-
 build/gobind-yggdrasil/monolith.go            |  2 +-
 clientapi/admin_test.go                       | 20 +++++------
 clientapi/clientapi_test.go                   | 26 +++++++--------
 clientapi/routing/joinroom_test.go            |  2 +-
 clientapi/routing/login_test.go               |  2 +-
 clientapi/routing/register_test.go            |  6 ++--
 .../monolith/monolith.go                      |  2 +-
 cmd/dendrite-demo-yggdrasil/main.go           |  2 +-
 cmd/dendrite/main.go                          |  2 +-
 dendrite-sample.yaml                          |  4 +++
 roomserver/roomserver_test.go                 |  6 ++--
 setup/config/config_userapi.go                |  5 +++
 userapi/consumers/devicelistupdate.go         |  6 +++-
 userapi/internal/device_list_update.go        | 33 +++++++++++++++++--
 userapi/internal/device_list_update_test.go   |  9 ++---
 userapi/userapi.go                            |  3 +-
 18 files changed, 92 insertions(+), 47 deletions(-)

diff --git a/appservice/appservice_test.go b/appservice/appservice_test.go
index ddc24477b..bbdeb47df 100644
--- a/appservice/appservice_test.go
+++ b/appservice/appservice_test.go
@@ -144,7 +144,7 @@ func TestAppserviceInternalAPI(t *testing.T) {
 		cm := sqlutil.NewConnectionManager(ctx, cfg.Global.DatabaseOptions)
 		rsAPI := roomserver.NewInternalAPI(ctx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		usrAPI := userapi.NewInternalAPI(ctx, cfg, cm, &natsInstance, rsAPI, nil)
+		usrAPI := userapi.NewInternalAPI(ctx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
 		asAPI := appservice.NewInternalAPI(ctx, cfg, &natsInstance, usrAPI, rsAPI)
 
 		runCases(t, asAPI)
@@ -239,7 +239,7 @@ func TestAppserviceInternalAPI_UnixSocket_Simple(t *testing.T) {
 	cm := sqlutil.NewConnectionManager(ctx, cfg.Global.DatabaseOptions)
 	rsAPI := roomserver.NewInternalAPI(ctx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 	rsAPI.SetFederationAPI(nil, nil)
-	usrAPI := userapi.NewInternalAPI(ctx, cfg, cm, &natsInstance, rsAPI, nil)
+	usrAPI := userapi.NewInternalAPI(ctx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
 	asAPI := appservice.NewInternalAPI(ctx, cfg, &natsInstance, usrAPI, rsAPI)
 
 	t.Run("UserIDExists", func(t *testing.T) {
@@ -378,7 +378,7 @@ func TestRoomserverConsumerOneInvite(t *testing.T) {
 		// Create required internal APIs
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		usrAPI := userapi.NewInternalAPI(processCtx, cfg, cm, natsInstance, rsAPI, nil)
+		usrAPI := userapi.NewInternalAPI(processCtx, cfg, cm, natsInstance, rsAPI, nil, caching.DisableMetrics)
 		// start the consumer
 		appservice.NewInternalAPI(processCtx, cfg, natsInstance, usrAPI, rsAPI)
 
diff --git a/build/dendritejs-pinecone/main.go b/build/dendritejs-pinecone/main.go
index 61baed902..d3d5f59fe 100644
--- a/build/dendritejs-pinecone/main.go
+++ b/build/dendritejs-pinecone/main.go
@@ -38,6 +38,7 @@ import (
 	"github.com/matrix-org/dendrite/setup/jetstream"
 	"github.com/matrix-org/dendrite/setup/process"
 	"github.com/matrix-org/dendrite/userapi"
+	"github.com/matrix-org/gomatrixserverlib/spec"
 
 	"github.com/matrix-org/gomatrixserverlib"
 
@@ -190,7 +191,7 @@ func startup() {
 	serverKeyAPI := &signing.YggdrasilKeys{}
 	keyRing := serverKeyAPI.KeyRing()
 
-	userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, federation)
+	userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, federation, caching.EnableMetrics)
 
 	asQuery := appservice.NewInternalAPI(
 		processCtx, cfg, &natsInstance, userAPI, rsAPI,
diff --git a/build/gobind-yggdrasil/monolith.go b/build/gobind-yggdrasil/monolith.go
index 720ce37eb..791ad261b 100644
--- a/build/gobind-yggdrasil/monolith.go
+++ b/build/gobind-yggdrasil/monolith.go
@@ -216,7 +216,7 @@ func (m *DendriteMonolith) Start() {
 		processCtx, cfg, cm, &natsInstance, federation, rsAPI, caches, keyRing, true,
 	)
 
-	userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, federation)
+	userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, federation, caching.EnableMetrics)
 
 	asAPI := appservice.NewInternalAPI(processCtx, cfg, &natsInstance, userAPI, rsAPI)
 	rsAPI.SetAppserviceAPI(asAPI)
diff --git a/clientapi/admin_test.go b/clientapi/admin_test.go
index 66667b03c..b228dd93c 100644
--- a/clientapi/admin_test.go
+++ b/clientapi/admin_test.go
@@ -45,7 +45,7 @@ func TestAdminCreateToken(t *testing.T) {
 		caches := caching.NewRistrettoCache(128*1024*1024, time.Hour, caching.DisableMetrics)
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
 		AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
 		accessTokens := map[*test.User]userDevice{
 			aliceAdmin: {},
@@ -196,7 +196,7 @@ func TestAdminListRegistrationTokens(t *testing.T) {
 		caches := caching.NewRistrettoCache(128*1024*1024, time.Hour, caching.DisableMetrics)
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
 		AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
 		accessTokens := map[*test.User]userDevice{
 			aliceAdmin: {},
@@ -314,7 +314,7 @@ func TestAdminGetRegistrationToken(t *testing.T) {
 		caches := caching.NewRistrettoCache(128*1024*1024, time.Hour, caching.DisableMetrics)
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
 		AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
 		accessTokens := map[*test.User]userDevice{
 			aliceAdmin: {},
@@ -415,7 +415,7 @@ func TestAdminDeleteRegistrationToken(t *testing.T) {
 		caches := caching.NewRistrettoCache(128*1024*1024, time.Hour, caching.DisableMetrics)
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
 		AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
 		accessTokens := map[*test.User]userDevice{
 			aliceAdmin: {},
@@ -509,7 +509,7 @@ func TestAdminUpdateRegistrationToken(t *testing.T) {
 		caches := caching.NewRistrettoCache(128*1024*1024, time.Hour, caching.DisableMetrics)
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
 		AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
 		accessTokens := map[*test.User]userDevice{
 			aliceAdmin: {},
@@ -693,7 +693,7 @@ func TestAdminResetPassword(t *testing.T) {
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
 		// Needed for changing the password/login
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
 		// We mostly need the userAPI for this test, so nil for other APIs/caches etc.
 		AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
 
@@ -791,7 +791,7 @@ func TestPurgeRoom(t *testing.T) {
 		fsAPI := federationapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, nil, rsAPI, caches, nil, true)
 		rsAPI.SetFederationAPI(fsAPI, nil)
 
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
 		syncapi.AddPublicRoutes(processCtx, routers, cfg, cm, &natsInstance, userAPI, rsAPI, caches, caching.DisableMetrics)
 
 		// Create the room
@@ -863,7 +863,7 @@ func TestAdminEvacuateRoom(t *testing.T) {
 		fsAPI := federationapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, nil, rsAPI, caches, nil, true)
 		rsAPI.SetFederationAPI(fsAPI, nil)
 
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
 
 		// Create the room
 		if err := api.SendEvents(ctx, rsAPI, api.KindNew, room.Events(), "test", "test", api.DoNotSendToOtherServers, nil, false); err != nil {
@@ -964,7 +964,7 @@ func TestAdminEvacuateUser(t *testing.T) {
 		fsAPI := federationapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, basepkg.CreateFederationClient(cfg, nil), rsAPI, caches, nil, true)
 		rsAPI.SetFederationAPI(fsAPI, nil)
 
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
 
 		// Create the room
 		if err := api.SendEvents(ctx, rsAPI, api.KindNew, room.Events(), "test", "test", api.DoNotSendToOtherServers, nil, false); err != nil {
@@ -1055,7 +1055,7 @@ func TestAdminMarkAsStale(t *testing.T) {
 		cm := sqlutil.NewConnectionManager(processCtx, cfg.Global.DatabaseOptions)
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
 
 		// We mostly need the rsAPI for this test, so nil for other APIs/caches etc.
 		AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
diff --git a/clientapi/clientapi_test.go b/clientapi/clientapi_test.go
index f2d617cb9..2bb15fba3 100644
--- a/clientapi/clientapi_test.go
+++ b/clientapi/clientapi_test.go
@@ -121,7 +121,7 @@ func TestGetPutDevices(t *testing.T) {
 		cm := sqlutil.NewConnectionManager(processCtx, cfg.Global.DatabaseOptions)
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
 
 		// We mostly need the rsAPI for this test, so nil for other APIs/caches etc.
 		AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
@@ -170,7 +170,7 @@ func TestDeleteDevice(t *testing.T) {
 		caches := caching.NewRistrettoCache(128*1024*1024, time.Hour, caching.DisableMetrics)
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
 
 		// We mostly need the rsAPI/ for this test, so nil for other APIs/caches etc.
 		AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
@@ -275,7 +275,7 @@ func TestDeleteDevices(t *testing.T) {
 		caches := caching.NewRistrettoCache(128*1024*1024, time.Hour, caching.DisableMetrics)
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
 
 		// We mostly need the rsAPI/ for this test, so nil for other APIs/caches etc.
 		AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
@@ -442,7 +442,7 @@ func TestSetDisplayname(t *testing.T) {
 
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, natsInstance, rsAPI, nil)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, natsInstance, rsAPI, nil, caching.DisableMetrics)
 		asPI := appservice.NewInternalAPI(processCtx, cfg, natsInstance, userAPI, rsAPI)
 
 		AddPublicRoutes(processCtx, routers, cfg, natsInstance, base.CreateFederationClient(cfg, nil), rsAPI, asPI, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
@@ -554,7 +554,7 @@ func TestSetAvatarURL(t *testing.T) {
 
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, natsInstance, rsAPI, nil)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, natsInstance, rsAPI, nil, caching.DisableMetrics)
 		asPI := appservice.NewInternalAPI(processCtx, cfg, natsInstance, userAPI, rsAPI)
 
 		AddPublicRoutes(processCtx, routers, cfg, natsInstance, base.CreateFederationClient(cfg, nil), rsAPI, asPI, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
@@ -632,7 +632,7 @@ func TestTyping(t *testing.T) {
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
 		// Needed to create accounts
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
 		// We mostly need the rsAPI/userAPI for this test, so nil for other APIs etc.
 		AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
 
@@ -716,7 +716,7 @@ func TestMembership(t *testing.T) {
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
 		// Needed to create accounts
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
 		rsAPI.SetUserAPI(userAPI)
 		// We mostly need the rsAPI/userAPI for this test, so nil for other APIs etc.
 		AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
@@ -955,7 +955,7 @@ func TestCapabilities(t *testing.T) {
 		// Needed to create accounts
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, nil, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
 		// We mostly need the rsAPI/userAPI for this test, so nil for other APIs etc.
 		AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
 
@@ -1002,7 +1002,7 @@ func TestTurnserver(t *testing.T) {
 	// Needed to create accounts
 	rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, nil, caching.DisableMetrics)
 	rsAPI.SetFederationAPI(nil, nil)
-	userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil)
+	userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
 	//rsAPI.SetUserAPI(userAPI)
 	// We mostly need the rsAPI/userAPI for this test, so nil for other APIs etc.
 	AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
@@ -1100,7 +1100,7 @@ func Test3PID(t *testing.T) {
 		// Needed to create accounts
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, nil, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
 		// We mostly need the rsAPI/userAPI for this test, so nil for other APIs etc.
 		AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
 
@@ -1276,7 +1276,7 @@ func TestPushRules(t *testing.T) {
 		cm := sqlutil.NewConnectionManager(processCtx, cfg.Global.DatabaseOptions)
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
 
 		// We mostly need the rsAPI for this test, so nil for other APIs/caches etc.
 		AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
@@ -1663,7 +1663,7 @@ func TestKeys(t *testing.T) {
 		cm := sqlutil.NewConnectionManager(processCtx, cfg.Global.DatabaseOptions)
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
 
 		// We mostly need the rsAPI for this test, so nil for other APIs/caches etc.
 		AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
@@ -2125,7 +2125,7 @@ func TestKeyBackup(t *testing.T) {
 		cm := sqlutil.NewConnectionManager(processCtx, cfg.Global.DatabaseOptions)
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
 
 		// We mostly need the rsAPI for this test, so nil for other APIs/caches etc.
 		AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
diff --git a/clientapi/routing/joinroom_test.go b/clientapi/routing/joinroom_test.go
index 933ea8d3a..be3fb429f 100644
--- a/clientapi/routing/joinroom_test.go
+++ b/clientapi/routing/joinroom_test.go
@@ -36,7 +36,7 @@ func TestJoinRoomByIDOrAlias(t *testing.T) {
 		natsInstance := jetstream.NATSInstance{}
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil) // creates the rs.Inputer etc
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
 		asAPI := appservice.NewInternalAPI(processCtx, cfg, &natsInstance, userAPI, rsAPI)
 
 		// Create the users in the userapi
diff --git a/clientapi/routing/login_test.go b/clientapi/routing/login_test.go
index 252017db2..4c4fc3533 100644
--- a/clientapi/routing/login_test.go
+++ b/clientapi/routing/login_test.go
@@ -49,7 +49,7 @@ func TestLogin(t *testing.T) {
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
 		// Needed for /login
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
 
 		// We mostly need the userAPI for this test, so nil for other APIs/caches etc.
 		Setup(routers, cfg, nil, nil, userAPI, nil, nil, nil, nil, nil, nil, nil, caching.DisableMetrics)
diff --git a/clientapi/routing/register_test.go b/clientapi/routing/register_test.go
index 0a1986cf7..69b29e9c2 100644
--- a/clientapi/routing/register_test.go
+++ b/clientapi/routing/register_test.go
@@ -416,7 +416,7 @@ func Test_register(t *testing.T) {
 		cm := sqlutil.NewConnectionManager(processCtx, cfg.Global.DatabaseOptions)
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
 
 		for _, tc := range testCases {
 			t.Run(tc.name, func(t *testing.T) {
@@ -596,7 +596,7 @@ func TestRegisterUserWithDisplayName(t *testing.T) {
 		cm := sqlutil.NewConnectionManager(processCtx, cfg.Global.DatabaseOptions)
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
 		deviceName, deviceID := "deviceName", "deviceID"
 		expectedDisplayName := "DisplayName"
 		response := completeRegistration(
@@ -637,7 +637,7 @@ func TestRegisterAdminUsingSharedSecret(t *testing.T) {
 		caches := caching.NewRistrettoCache(128*1024*1024, time.Hour, caching.DisableMetrics)
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
 
 		expectedDisplayName := "rabbit"
 		jsonStr := []byte(`{"admin":true,"mac":"24dca3bba410e43fe64b9b5c28306693bf3baa9f","nonce":"759f047f312b99ff428b21d581256f8592b8976e58bc1b543972dc6147e529a79657605b52d7becd160ff5137f3de11975684319187e06901955f79e5a6c5a79","password":"wonderland","username":"alice","displayname":"rabbit"}`)
diff --git a/cmd/dendrite-demo-pinecone/monolith/monolith.go b/cmd/dendrite-demo-pinecone/monolith/monolith.go
index 41af568a6..5222d0b8e 100644
--- a/cmd/dendrite-demo-pinecone/monolith/monolith.go
+++ b/cmd/dendrite-demo-pinecone/monolith/monolith.go
@@ -145,7 +145,7 @@ func (p *P2PMonolith) SetupDendrite(
 	)
 	rsAPI.SetFederationAPI(fsAPI, keyRing)
 
-	userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, federation)
+	userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, federation, enableMetrics)
 
 	asAPI := appservice.NewInternalAPI(processCtx, cfg, &natsInstance, userAPI, rsAPI)
 
diff --git a/cmd/dendrite-demo-yggdrasil/main.go b/cmd/dendrite-demo-yggdrasil/main.go
index 3ec550113..b07687538 100644
--- a/cmd/dendrite-demo-yggdrasil/main.go
+++ b/cmd/dendrite-demo-yggdrasil/main.go
@@ -213,7 +213,7 @@ func main() {
 	natsInstance := jetstream.NATSInstance{}
 	rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.EnableMetrics)
 
-	userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, federation)
+	userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, federation, caching.EnableMetrics)
 
 	asAPI := appservice.NewInternalAPI(processCtx, cfg, &natsInstance, userAPI, rsAPI)
 	rsAPI.SetAppserviceAPI(asAPI)
diff --git a/cmd/dendrite/main.go b/cmd/dendrite/main.go
index f3140b4e2..f38263c6c 100644
--- a/cmd/dendrite/main.go
+++ b/cmd/dendrite/main.go
@@ -162,7 +162,7 @@ func main() {
 	// dependency. Other components also need updating after their dependencies are up.
 	rsAPI.SetFederationAPI(fsAPI, keyRing)
 
-	userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, federationClient)
+	userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, federationClient, caching.EnableMetrics)
 	asAPI := appservice.NewInternalAPI(processCtx, cfg, &natsInstance, userAPI, rsAPI)
 
 	rsAPI.SetAppserviceAPI(asAPI)
diff --git a/dendrite-sample.yaml b/dendrite-sample.yaml
index 7affc2599..e143a7398 100644
--- a/dendrite-sample.yaml
+++ b/dendrite-sample.yaml
@@ -325,6 +325,10 @@ user_api:
   auto_join_rooms:
   #  - "#main:matrix.org"
 
+  # The number of workers to start for the DeviceListUpdater. Defaults to 8.
+  # This only needs updating if the "InputDeviceListUpdate" stream keeps growing indefinitely.
+  # worker_count: 8
+
 # Configuration for Opentracing.
 # See https://github.com/matrix-org/dendrite/tree/master/docs/tracing for information on
 # how this works and how to set it up.
diff --git a/roomserver/roomserver_test.go b/roomserver/roomserver_test.go
index 90e67b699..22d27ba05 100644
--- a/roomserver/roomserver_test.go
+++ b/roomserver/roomserver_test.go
@@ -58,7 +58,7 @@ func TestUsers(t *testing.T) {
 		})
 
 		t.Run("kick users", func(t *testing.T) {
-			usrAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil)
+			usrAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
 			rsAPI.SetUserAPI(usrAPI)
 			testKickUsers(t, rsAPI, usrAPI)
 		})
@@ -258,7 +258,7 @@ func TestPurgeRoom(t *testing.T) {
 		fsAPI := federationapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, nil, rsAPI, caches, nil, true)
 		rsAPI.SetFederationAPI(fsAPI, nil)
 
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
 		syncapi.AddPublicRoutes(processCtx, routers, cfg, cm, &natsInstance, userAPI, rsAPI, caches, caching.DisableMetrics)
 
 		// Create the room
@@ -1050,7 +1050,7 @@ func TestUpgrade(t *testing.T) {
 
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
 		rsAPI.SetUserAPI(userAPI)
 
 		for _, tc := range testCases {
diff --git a/setup/config/config_userapi.go b/setup/config/config_userapi.go
index e64a3910c..559de72ac 100644
--- a/setup/config/config_userapi.go
+++ b/setup/config/config_userapi.go
@@ -21,6 +21,10 @@ type UserAPI struct {
 	// Users who register on this homeserver will automatically
 	// be joined to the rooms listed under this option.
 	AutoJoinRooms []string `yaml:"auto_join_rooms"`
+
+	// The number of workers to start for the DeviceListUpdater. Defaults to 8.
+	// This only needs updating if the "InputDeviceListUpdate" stream keeps growing indefinitely.
+	WorkerCount int `yaml:"worker_count"`
 }
 
 const DefaultOpenIDTokenLifetimeMS = 3600000 // 60 minutes
@@ -28,6 +32,7 @@ const DefaultOpenIDTokenLifetimeMS = 3600000 // 60 minutes
 func (c *UserAPI) Defaults(opts DefaultOpts) {
 	c.BCryptCost = bcrypt.DefaultCost
 	c.OpenIDTokenLifetimeMS = DefaultOpenIDTokenLifetimeMS
+	c.WorkerCount = 8
 	if opts.Generate {
 		if !opts.SingleDatabase {
 			c.AccountDatabase.ConnectionString = "file:userapi_accounts.db"
diff --git a/userapi/consumers/devicelistupdate.go b/userapi/consumers/devicelistupdate.go
index 3389bb808..b3ccb573b 100644
--- a/userapi/consumers/devicelistupdate.go
+++ b/userapi/consumers/devicelistupdate.go
@@ -17,6 +17,7 @@ package consumers
 import (
 	"context"
 	"encoding/json"
+	"time"
 
 	"github.com/matrix-org/dendrite/userapi/internal"
 	"github.com/matrix-org/gomatrixserverlib"
@@ -82,7 +83,10 @@ func (t *DeviceListUpdateConsumer) onMessage(ctx context.Context, msgs []*nats.M
 		return true
 	}
 
-	err := t.updater.Update(ctx, m)
+	timeoutCtx, cancel := context.WithTimeout(ctx, time.Second*30)
+	defer cancel()
+
+	err := t.updater.Update(timeoutCtx, m)
 	if err != nil {
 		logrus.WithFields(logrus.Fields{
 			"user_id":   m.UserID,
diff --git a/userapi/internal/device_list_update.go b/userapi/internal/device_list_update.go
index 2f33589fe..a4d28188a 100644
--- a/userapi/internal/device_list_update.go
+++ b/userapi/internal/device_list_update.go
@@ -21,6 +21,7 @@ import (
 	"fmt"
 	"hash/fnv"
 	"net"
+	"strconv"
 	"sync"
 	"time"
 
@@ -142,13 +143,36 @@ type KeyChangeProducer interface {
 	ProduceKeyChanges(keys []api.DeviceMessage) error
 }
 
+var deviceListUpdaterBackpressure = prometheus.NewGaugeVec(
+	prometheus.GaugeOpts{
+		Namespace: "dendrite",
+		Subsystem: "keyserver",
+		Name:      "worker_backpressure",
+		Help:      "How many device list updater requests are queued",
+	},
+	[]string{"worker_id"},
+)
+var deviceListUpdaterServersRetrying = prometheus.NewGaugeVec(
+	prometheus.GaugeOpts{
+		Namespace: "dendrite",
+		Subsystem: "keyserver",
+		Name:      "worker_servers_retrying",
+		Help:      "How many servers are queued for retry",
+	},
+	[]string{"worker_id"},
+)
+
 // NewDeviceListUpdater creates a new updater which fetches fresh device lists when they go stale.
 func NewDeviceListUpdater(
 	process *process.ProcessContext, db DeviceListUpdaterDatabase,
 	api DeviceListUpdaterAPI, producer KeyChangeProducer,
 	fedClient fedsenderapi.KeyserverFederationAPI, numWorkers int,
 	rsAPI rsapi.KeyserverRoomserverAPI, thisServer spec.ServerName,
+	enableMetrics bool,
 ) *DeviceListUpdater {
+	if enableMetrics {
+		prometheus.MustRegister(deviceListUpdaterBackpressure, deviceListUpdaterServersRetrying)
+	}
 	return &DeviceListUpdater{
 		process:        process,
 		userIDToMutex:  make(map[string]*sync.Mutex),
@@ -173,7 +197,7 @@ func (u *DeviceListUpdater) Start() error {
 		// to stop (in this transaction) until key requests can be made.
 		ch := make(chan spec.ServerName, 10)
 		u.workerChans[i] = ch
-		go u.worker(ch)
+		go u.worker(ch, i)
 	}
 
 	staleLists, err := u.db.StaleDeviceLists(u.process.Context(), []spec.ServerName{})
@@ -343,6 +367,8 @@ func (u *DeviceListUpdater) notifyWorkers(userID string) {
 	index := int(int64(hash.Sum32()) % int64(len(u.workerChans)))
 
 	ch := u.assignChannel(userID)
+	deviceListUpdaterBackpressure.With(prometheus.Labels{"worker_id": strconv.Itoa(index)}).Inc()
+	defer deviceListUpdaterBackpressure.With(prometheus.Labels{"worker_id": strconv.Itoa(index)}).Dec()
 	u.workerChans[index] <- remoteServer
 	select {
 	case <-ch:
@@ -372,7 +398,7 @@ func (u *DeviceListUpdater) clearChannel(userID string) {
 	}
 }
 
-func (u *DeviceListUpdater) worker(ch chan spec.ServerName) {
+func (u *DeviceListUpdater) worker(ch chan spec.ServerName, workerID int) {
 	retries := make(map[spec.ServerName]time.Time)
 	retriesMu := &sync.Mutex{}
 	// restarter goroutine which will inject failed servers into ch when it is time
@@ -391,9 +417,12 @@ func (u *DeviceListUpdater) worker(ch chan spec.ServerName) {
 			for _, srv := range serversToRetry {
 				delete(retries, srv)
 			}
+			deviceListUpdaterServersRetrying.With(prometheus.Labels{"worker_id": strconv.Itoa(workerID)}).Set(float64(len(retries)))
 			retriesMu.Unlock()
 			for _, srv := range serversToRetry {
+				deviceListUpdaterBackpressure.With(prometheus.Labels{"worker_id": strconv.Itoa(workerID)}).Inc()
 				ch <- srv
+				deviceListUpdaterBackpressure.With(prometheus.Labels{"worker_id": strconv.Itoa(workerID)}).Dec()
 			}
 		}
 	}()
diff --git a/userapi/internal/device_list_update_test.go b/userapi/internal/device_list_update_test.go
index 38fd8b583..14a49bc54 100644
--- a/userapi/internal/device_list_update_test.go
+++ b/userapi/internal/device_list_update_test.go
@@ -27,6 +27,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/matrix-org/dendrite/internal/caching"
 	"github.com/matrix-org/dendrite/internal/sqlutil"
 	"github.com/matrix-org/gomatrixserverlib"
 	"github.com/matrix-org/gomatrixserverlib/fclient"
@@ -161,7 +162,7 @@ func TestUpdateHavePrevID(t *testing.T) {
 	}
 	ap := &mockDeviceListUpdaterAPI{}
 	producer := &mockKeyChangeProducer{}
-	updater := NewDeviceListUpdater(process.NewProcessContext(), db, ap, producer, nil, 1, nil, "localhost")
+	updater := NewDeviceListUpdater(process.NewProcessContext(), db, ap, producer, nil, 1, nil, "localhost", caching.DisableMetrics)
 	event := gomatrixserverlib.DeviceListUpdateEvent{
 		DeviceDisplayName: "Foo Bar",
 		Deleted:           false,
@@ -233,7 +234,7 @@ func TestUpdateNoPrevID(t *testing.T) {
 			`)),
 		}, nil
 	})
-	updater := NewDeviceListUpdater(process.NewProcessContext(), db, ap, producer, fedClient, 2, nil, "example.test")
+	updater := NewDeviceListUpdater(process.NewProcessContext(), db, ap, producer, fedClient, 2, nil, "example.test", caching.DisableMetrics)
 	if err := updater.Start(); err != nil {
 		t.Fatalf("failed to start updater: %s", err)
 	}
@@ -303,7 +304,7 @@ func TestDebounce(t *testing.T) {
 		close(incomingFedReq)
 		return <-fedCh, nil
 	})
-	updater := NewDeviceListUpdater(process.NewProcessContext(), db, ap, producer, fedClient, 1, nil, "localhost")
+	updater := NewDeviceListUpdater(process.NewProcessContext(), db, ap, producer, fedClient, 1, nil, "localhost", caching.DisableMetrics)
 	if err := updater.Start(); err != nil {
 		t.Fatalf("failed to start updater: %s", err)
 	}
@@ -406,7 +407,7 @@ func TestDeviceListUpdater_CleanUp(t *testing.T) {
 
 		updater := NewDeviceListUpdater(processCtx, db, nil,
 			nil, nil,
-			0, rsAPI, "test")
+			0, rsAPI, "test", caching.DisableMetrics)
 		if err := updater.CleanUp(); err != nil {
 			t.Error(err)
 		}
diff --git a/userapi/userapi.go b/userapi/userapi.go
index 6b6dac884..34bf119a0 100644
--- a/userapi/userapi.go
+++ b/userapi/userapi.go
@@ -46,6 +46,7 @@ func NewInternalAPI(
 	natsInstance *jetstream.NATSInstance,
 	rsAPI rsapi.UserRoomserverAPI,
 	fedClient fedsenderapi.KeyserverFederationAPI,
+	enableMetrics bool,
 ) *internal.UserInternalAPI {
 	js, _ := natsInstance.Prepare(processContext, &dendriteCfg.Global.JetStream)
 	appServices := dendriteCfg.Derived.ApplicationServices
@@ -99,7 +100,7 @@ func NewInternalAPI(
 		FedClient:            fedClient,
 	}
 
-	updater := internal.NewDeviceListUpdater(processContext, keyDB, userAPI, keyChangeProducer, fedClient, 8, rsAPI, dendriteCfg.Global.ServerName) // 8 workers TODO: configurable
+	updater := internal.NewDeviceListUpdater(processContext, keyDB, userAPI, keyChangeProducer, fedClient, dendriteCfg.UserAPI.WorkerCount, rsAPI, dendriteCfg.Global.ServerName, enableMetrics)
 	userAPI.Updater = updater
 	// Remove users which we don't share a room with anymore
 	if err := updater.CleanUp(); err != nil {