[chore/performance] Make sender multiplier configurable

docs/configuration/advanced.md

@@ -79,4 +79,36 @@ advanced-rate-limit-requests: 300
 # Examples: [8, 4, 9, 0]
 # Default: 8
 advanced-throttling-multiplier: 8
+
+# Int. CPU multiplier for the amount of goroutines to spawn in order to send messages via ActivityPub.
+# Messages will be batched so that at most multiplier * CPU count messages will be sent out at once.
+# This can be tuned to limit concurrent POSTing to remote inboxes, preventing your instance CPU
+# usage from skyrocketing when an account with many followers posts a new status.
+#
+# Messages are split among available senders, and each sender processes its assigned messages in serial.
+# For example, say a user with 1000 followers is on an instance with 2 CPUs. With the default multiplier
+# of 2, this means 4 senders would be in process at once on this instance. When the user creates a new post,
+# each sender would end up iterating through about 250 Create messages + delivering them to remote instances.
+#
+# If you set this to 0 or less, only 1 sender will be used regardless of CPU count. This may be
+# useful in cases where you are working with very tight network or CPU constraints.
+#
+# Example values for multiplier 2 (default):
+#
+# 1 cpu = 2 concurrent senders
+# 2 cpu = 4 concurrent senders
+# 4 cpu = 8 concurrent senders
+#
+# Example values for multiplier 4:
+#
+# 1 cpu = 4 concurrent senders
+# 2 cpu = 8 concurrent senders
+# 4 cpu = 16 concurrent senders
+#
+# Example values for multiplier <1:
+#
+# 1 cpu = 1 concurrent sender
+# 2 cpu = 1 concurrent sender
+# 4 cpu = 1 concurrent sender
+advanced-sender-multiplier: 2
 ```

example/config.yaml

@@ -848,3 +848,35 @@ advanced-throttling-multiplier: 8
 # Examples: [30s, 10s, 5s, 1m]
 # Default: 30s
 advanced-throttling-retry-after: "30s"
+
+# Int. CPU multiplier for the amount of goroutines to spawn in order to send messages via ActivityPub.
+# Messages will be batched so that at most multiplier * CPU count messages will be sent out at once.
+# This can be tuned to limit concurrent POSTing to remote inboxes, preventing your instance CPU
+# usage from skyrocketing when an account with many followers posts a new status.
+#
+# Messages are split among available senders, and each sender processes its assigned messages in serial.
+# For example, say a user with 1000 followers is on an instance with 2 CPUs. With the default multiplier
+# of 2, this means 4 senders would be in process at once on this instance. When the user creates a new post,
+# each sender would end up iterating through about 250 Create messages + delivering them to remote instances.
+#
+# If you set this to 0 or less, only 1 sender will be used regardless of CPU count. This may be
+# useful in cases where you are working with very tight network or CPU constraints.
+#
+# Example values for multiplier 2 (default):
+#
+# 1 cpu = 2 concurrent senders
+# 2 cpu = 4 concurrent senders
+# 4 cpu = 8 concurrent senders
+#
+# Example values for multiplier 4:
+#
+# 1 cpu = 4 concurrent senders
+# 2 cpu = 8 concurrent senders
+# 4 cpu = 16 concurrent senders
+#
+# Example values for multiplier <1:
+#
+# 1 cpu = 1 concurrent sender
+# 2 cpu = 1 concurrent sender
+# 4 cpu = 1 concurrent sender
+advanced-sender-multiplier: 2

internal/config/config.go

@@ -141,6 +141,7 @@ type Configuration struct {
 	AdvancedRateLimitRequests    int           `name:"advanced-rate-limit-requests" usage:"Amount of HTTP requests to permit within a 5 minute window. 0 or less turns rate limiting off."`
 	AdvancedThrottlingMultiplier int           `name:"advanced-throttling-multiplier" usage:"Multiplier to use per cpu for http request throttling. 0 or less turns throttling off."`
 	AdvancedThrottlingRetryAfter time.Duration `name:"advanced-throttling-retry-after" usage:"Retry-After duration response to send for throttled requests."`
+	AdvancedSenderMultiplier     int           `name:"advanced-sender-multiplier" usage:"Multiplier to use per cpu for batching outgoing fedi messages. 0 or less turns batching off (not recommended)."`
 
 	// Cache configuration vars.
 	Cache CacheConfiguration `name:"cache"`

internal/config/defaults.go

@@ -116,6 +116,7 @@ var Defaults = Configuration{
 	AdvancedCookiesSamesite:      "lax",
 	AdvancedRateLimitRequests:    300, // 1 per second per 5 minutes
 	AdvancedThrottlingMultiplier: 8,   // 8 open requests per CPU
+	AdvancedSenderMultiplier:     2,   // 2 senders per CPU
 
 	Cache: CacheConfiguration{
 		GTS: GTSCacheConfiguration{

internal/config/flags.go

@@ -144,6 +144,7 @@ func (s *ConfigState) AddServerFlags(cmd *cobra.Command) {
 		cmd.Flags().Int(AdvancedRateLimitRequestsFlag(), cfg.AdvancedRateLimitRequests, fieldtag("AdvancedRateLimitRequests", "usage"))
 		cmd.Flags().Int(AdvancedThrottlingMultiplierFlag(), cfg.AdvancedThrottlingMultiplier, fieldtag("AdvancedThrottlingMultiplier", "usage"))
 		cmd.Flags().Duration(AdvancedThrottlingRetryAfterFlag(), cfg.AdvancedThrottlingRetryAfter, fieldtag("AdvancedThrottlingRetryAfter", "usage"))
+		cmd.Flags().Int(AdvancedSenderMultiplierFlag(), cfg.AdvancedSenderMultiplier, fieldtag("AdvancedSenderMultiplier", "usage"))
 
 		cmd.Flags().String(RequestIDHeaderFlag(), cfg.RequestIDHeader, fieldtag("RequestIDHeader", "usage"))
 	})

internal/config/helpers.gen.go

@@ -2124,6 +2124,31 @@ func GetAdvancedThrottlingRetryAfter() time.Duration { return global.GetAdvanced
 // SetAdvancedThrottlingRetryAfter safely sets the value for global configuration 'AdvancedThrottlingRetryAfter' field
 func SetAdvancedThrottlingRetryAfter(v time.Duration) { global.SetAdvancedThrottlingRetryAfter(v) }
 
+// GetAdvancedSenderMultiplier safely fetches the Configuration value for state's 'AdvancedSenderMultiplier' field
+func (st *ConfigState) GetAdvancedSenderMultiplier() (v int) {
+	st.mutex.Lock()
+	v = st.config.AdvancedSenderMultiplier
+	st.mutex.Unlock()
+	return
+}
+
+// SetAdvancedSenderMultiplier safely sets the Configuration value for state's 'AdvancedSenderMultiplier' field
+func (st *ConfigState) SetAdvancedSenderMultiplier(v int) {
+	st.mutex.Lock()
+	defer st.mutex.Unlock()
+	st.config.AdvancedSenderMultiplier = v
+	st.reloadToViper()
+}
+
+// AdvancedSenderMultiplierFlag returns the flag name for the 'AdvancedSenderMultiplier' field
+func AdvancedSenderMultiplierFlag() string { return "advanced-sender-multiplier" }
+
+// GetAdvancedSenderMultiplier safely fetches the value for global configuration 'AdvancedSenderMultiplier' field
+func GetAdvancedSenderMultiplier() int { return global.GetAdvancedSenderMultiplier() }
+
+// SetAdvancedSenderMultiplier safely sets the value for global configuration 'AdvancedSenderMultiplier' field
+func SetAdvancedSenderMultiplier(v int) { global.SetAdvancedSenderMultiplier(v) }
+
 // GetCacheGTSAccountMaxSize safely fetches the Configuration value for state's 'Cache.GTS.AccountMaxSize' field
 func (st *ConfigState) GetCacheGTSAccountMaxSize() (v int) {
 	st.mutex.Lock()

internal/transport/controller.go

@@ -57,10 +57,19 @@ type controller struct {
 
 // NewController returns an implementation of the Controller interface for creating new transports
 func NewController(state *state.State, federatingDB federatingdb.DB, clock pub.Clock, client httpclient.SigningClient) Controller {
-	applicationName := config.GetApplicationName()
-	host := config.GetHost()
-	proto := config.GetProtocol()
-	version := config.GetSoftwareVersion()
+	var (
+		applicationName  = config.GetApplicationName()
+		host             = config.GetHost()
+		proto            = config.GetProtocol()
+		version          = config.GetSoftwareVersion()
+		senderMultiplier = config.GetAdvancedSenderMultiplier()
+	)
+
+	senders := senderMultiplier * runtime.GOMAXPROCS(0)
+	if senders < 1 {
+		// Clamp senders to 1.
+		senders = 1
+	}
 
 	c := &controller{
 		state:     state,
@@ -69,7 +78,7 @@ func NewController(state *state.State, federatingDB federatingdb.DB, clock pub.C
 		client:    client,
 		trspCache: cache.New[string, *transport](0, 100, 0),
 		userAgent: fmt.Sprintf("%s (+%s://%s) gotosocial/%s", applicationName, proto, host, version),
-		senders:   2 * runtime.GOMAXPROCS(0), // on batch delivery, only ever send 2*GOMAXPROCS at a time.
+		senders:   senders,
 	}
 
 	return c

test/envparsing.sh

@@ -11,6 +11,7 @@ EXPECT=$(cat <<"EOF"
     "accounts-registration-open": true,
     "advanced-cookies-samesite": "strict",
     "advanced-rate-limit-requests": 6969,
+    "advanced-sender-multiplier": -1,
     "advanced-throttling-multiplier": -1,
     "advanced-throttling-retry-after": 10000000000,
     "application-name": "gts",
@@ -241,6 +242,7 @@ GTS_SYSLOG_PROTOCOL='udp' \
 GTS_SYSLOG_ADDRESS='127.0.0.1:6969' \
 GTS_ADVANCED_COOKIES_SAMESITE='strict' \
 GTS_ADVANCED_RATE_LIMIT_REQUESTS=6969 \
+GTS_ADVANCED_SENDER_MULTIPLIER=-1 \
 GTS_ADVANCED_THROTTLING_MULTIPLIER=-1 \
 GTS_ADVANCED_THROTTLING_RETRY_AFTER='10s' \
 GTS_REQUEST_ID_HEADER='X-Trace-Id' \

testrig/config.go

@@ -120,6 +120,7 @@ var testDefaults = config.Configuration{
 	AdvancedCookiesSamesite:      "lax",
 	AdvancedRateLimitRequests:    0, // disabled
 	AdvancedThrottlingMultiplier: 0, // disabled
+	AdvancedSenderMultiplier:     0, // 1 sender only, regardless of CPU
 
 	SoftwareVersion: "0.0.0-testrig",