Move update_client_ip background job from the main process to the background worker.

changelog.d/12251.feature

@@ -0,0 +1 @@
+Offload the `update_client_ip` background job from the main process to the background worker, when using Redis-based replication.

synapse/app/admin_cmd.py

@@ -33,7 +33,6 @@
 from synapse.replication.slave.storage._base import BaseSlavedStore
 from synapse.replication.slave.storage.account_data import SlavedAccountDataStore
 from synapse.replication.slave.storage.appservice import SlavedApplicationServiceStore
-from synapse.replication.slave.storage.client_ips import SlavedClientIpStore
 from synapse.replication.slave.storage.deviceinbox import SlavedDeviceInboxStore
 from synapse.replication.slave.storage.devices import SlavedDeviceStore
 from synapse.replication.slave.storage.events import SlavedEventStore
@@ -61,7 +60,6 @@ class AdminCmdSlavedStore(
     SlavedDeviceStore,
     SlavedPushRuleStore,
     SlavedEventStore,
-    SlavedClientIpStore,
     BaseSlavedStore,
     RoomWorkerStore,
 ):

synapse/app/generic_worker.py

@@ -53,7 +53,6 @@
 from synapse.replication.slave.storage._base import BaseSlavedStore
 from synapse.replication.slave.storage.account_data import SlavedAccountDataStore
 from synapse.replication.slave.storage.appservice import SlavedApplicationServiceStore
-from synapse.replication.slave.storage.client_ips import SlavedClientIpStore
 from synapse.replication.slave.storage.deviceinbox import SlavedDeviceInboxStore
 from synapse.replication.slave.storage.devices import SlavedDeviceStore
 from synapse.replication.slave.storage.directory import DirectoryStore
@@ -247,7 +246,6 @@ class GenericWorkerSlavedStore(
     SlavedApplicationServiceStore,
     SlavedRegistrationStore,
     SlavedProfileStore,
-    SlavedClientIpStore,
     SlavedFilteringStore,
     MonthlyActiveUsersWorkerStore,
     MediaRepositoryStore,

synapse/replication/tcp/commands.py

@@ -356,7 +356,7 @@ def __init__(
         access_token: str,
         ip: str,
         user_agent: str,
-        device_id: str,
+        device_id: Optional[str],
         last_seen: int,
     ):
         self.user_id = user_id
@@ -389,6 +389,12 @@ def to_line(self) -> str:
             )
         )
 
+    def __repr__(self) -> str:
+        return (
+            f"UserIpCommand({self.user_id!r}, .., {self.ip!r}, "
+            f"{self.user_agent!r}, {self.device_id!r}, {self.last_seen})"
+        )
+
 
 class RemoteServerUpCommand(_SimpleCommand):
     """Sent when a worker has detected that a remote server is no longer

synapse/replication/tcp/handler.py

@@ -235,6 +235,14 @@ def __init__(self, hs: "HomeServer"):
         if self._is_master:
             self._server_notices_sender = hs.get_server_notices_sender()
 
+        if hs.config.redis.redis_enabled:
+            # If we're using Redis, it's the background worker that should
+            # receive USER_IP commands and store the relevant client IPs.
+            self._should_insert_client_ips = hs.config.worker.run_background_tasks
+        else:
+            # If we're NOT using Redis, this must be handled by the master
+            self._should_insert_client_ips = hs.get_instance_name() == "master"
+
     def _add_command_to_stream_queue(
         self, conn: IReplicationConnection, cmd: Union[RdataCommand, PositionCommand]
     ) -> None:
@@ -401,23 +409,37 @@ def on_USER_IP(
     ) -> Optional[Awaitable[None]]:
         user_ip_cache_counter.inc()
 
-        if self._is_master:
+        if self._is_master or self._should_insert_client_ips:
+            # We make a point of only returning an awaitable if there's actually
+            # something to do; on_USER_IP is not an async function, but
+            # _handle_user_ip is.
+            # If on_USER_IP returns an awaitable, it gets scheduled as a
+            # background process (see `BaseReplicationStreamProtocol.handle_command`).
             return self._handle_user_ip(cmd)
         else:
+            # Returning None when this process definitely has nothing to do
+            # reduces the overhead of handling the USER_IP command, which is
+            # currently broadcast to all workers regardless of utility.
             return None
 
     async def _handle_user_ip(self, cmd: UserIpCommand) -> None:
-        await self._store.insert_client_ip(
-            cmd.user_id,
-            cmd.access_token,
-            cmd.ip,
-            cmd.user_agent,
-            cmd.device_id,
-            cmd.last_seen,
-        )
-
-        assert self._server_notices_sender is not None
-        await self._server_notices_sender.on_user_ip(cmd.user_id)
+        """
+        Handles a User IP, branching depending on whether we are the main process
+        and/or the background worker.
+        """
+        if self._is_master:
+            assert self._server_notices_sender is not None
+            await self._server_notices_sender.on_user_ip(cmd.user_id)
+
+        if self._should_insert_client_ips:
+            await self._store.insert_client_ip(
+                cmd.user_id,
+                cmd.access_token,
+                cmd.ip,
+                cmd.user_agent,
+                cmd.device_id,
+                cmd.last_seen,
+            )
 
     def on_RDATA(self, conn: IReplicationConnection, cmd: RdataCommand) -> None:
         if cmd.instance_name == self._instance_name:
@@ -698,7 +720,7 @@ def send_user_ip(
         access_token: str,
         ip: str,
         user_agent: str,
-        device_id: str,
+        device_id: Optional[str],
         last_seen: int,
     ) -> None:
         """Tell the master that the user made a request."""

synapse/storage/databases/main/__init__.py

@@ -33,7 +33,7 @@
 from .appservice import ApplicationServiceStore, ApplicationServiceTransactionStore
 from .cache import CacheInvalidationWorkerStore
 from .censor_events import CensorEventsStore
-from .client_ips import ClientIpStore
+from .client_ips import ClientIpWorkerStore
 from .deviceinbox import DeviceInboxStore
 from .devices import DeviceStore
 from .directory import DirectoryStore
@@ -49,7 +49,7 @@
 from .lock import LockStore
 from .media_repository import MediaRepositoryStore
 from .metrics import ServerMetricsStore
-from .monthly_active_users import MonthlyActiveUsersStore
+from .monthly_active_users import MonthlyActiveUsersWorkerStore
 from .openid import OpenIdStore
 from .presence import PresenceStore
 from .profile import ProfileStore
@@ -112,13 +112,13 @@ class DataStore(
     AccountDataStore,
     EventPushActionsStore,
     OpenIdStore,
-    ClientIpStore,
+    ClientIpWorkerStore,
     DeviceStore,
     DeviceInboxStore,
     UserDirectoryStore,
     GroupServerStore,
     UserErasureStore,
-    MonthlyActiveUsersStore,
+    MonthlyActiveUsersWorkerStore,
     StatsStore,
     RelationsStore,
     CensorEventsStore,