Add config settings for background update parameters (#11980)

4 files changed, 97 insertions, 14 deletions

diff --git a/synapse/config/_base.pyi b/synapse/config/_base.pyi
index 1eb5f5a68c..363d8b4554 100644
--- a/synapse/config/_base.pyi
+++ b/synapse/config/_base.pyi
@@ -19,6 +19,7 @@ from synapse.config import (
     api,
     appservice,
     auth,
+    background_updates,
     cache,
     captcha,
     cas,
@@ -113,6 +114,7 @@ class RootConfig:
     caches: cache.CacheConfig
     federation: federation.FederationConfig
     retention: retention.RetentionConfig
+    background_updates: background_updates.BackgroundUpdateConfig
 
     config_classes: List[Type["Config"]] = ...
     def __init__(self) -> None: ...
diff --git a/synapse/config/background_updates.py b/synapse/config/background_updates.py
new file mode 100644
index 0000000000..f6cdeacc4b
--- /dev/null
+++ b/synapse/config/background_updates.py
@@ -0,0 +1,68 @@
+# Copyright 2022 Matrix.org Foundation C.I.C.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from ._base import Config
+
+
+class BackgroundUpdateConfig(Config):
+    section = "background_updates"
+
+    def generate_config_section(self, **kwargs) -> str:
+        return """\
+        ## Background Updates ##
+
+        # Background updates are database updates that are run in the background in batches.
+        # The duration, minimum batch size, default batch size, whether to sleep between batches and if so, how long to
+        # sleep can all be configured. This is helpful to speed up or slow down the updates.
+        #
+        background_updates:
+            # How long in milliseconds to run a batch of background updates for. Defaults to 100. Uncomment and set
+            # a time to change the default.
+            #
+            #background_update_duration_ms: 500
+
+            # Whether to sleep between updates. Defaults to True. Uncomment to change the default.
+            #
+            #sleep_enabled: false
+
+            # If sleeping between updates, how long in milliseconds to sleep for. Defaults to 1000. Uncomment
+            # and set a duration to change the default.
+            #
+            #sleep_duration_ms: 300
+
+            # Minimum size a batch of background updates can be. Must be greater than 0. Defaults to 1. Uncomment and
+            # set a size to change the default.
+            #
+            #min_batch_size: 10
+
+            # The batch size to use for the first iteration of a new background update. The default is 100.
+            # Uncomment and set a size to change the default.
+            #
+            #default_batch_size: 50
+        """
+
+    def read_config(self, config, **kwargs) -> None:
+        bg_update_config = config.get("background_updates") or {}
+
+        self.update_duration_ms = bg_update_config.get(
+            "background_update_duration_ms", 100
+        )
+
+        self.sleep_enabled = bg_update_config.get("sleep_enabled", True)
+
+        self.sleep_duration_ms = bg_update_config.get("sleep_duration_ms", 1000)
+
+        self.min_batch_size = bg_update_config.get("min_batch_size", 1)
+
+        self.default_batch_size = bg_update_config.get("default_batch_size", 100)
diff --git a/synapse/config/homeserver.py b/synapse/config/homeserver.py
index 001605c265..a4ec706908 100644
--- a/synapse/config/homeserver.py
+++ b/synapse/config/homeserver.py
@@ -16,6 +16,7 @@ from .account_validity import AccountValidityConfig
 from .api import ApiConfig
 from .appservice import AppServiceConfig
 from .auth import AuthConfig
+from .background_updates import BackgroundUpdateConfig
 from .cache import CacheConfig
 from .captcha import CaptchaConfig
 from .cas import CasConfig
@@ -99,4 +100,5 @@ class HomeServerConfig(RootConfig):
         WorkerConfig,
         RedisConfig,
         ExperimentalConfig,
+        BackgroundUpdateConfig,
     ]
diff --git a/synapse/storage/background_updates.py b/synapse/storage/background_updates.py
index 4acc2c997d..08c6eabc6d 100644
--- a/synapse/storage/background_updates.py
+++ b/synapse/storage/background_updates.py
@@ -60,18 +60,19 @@ class _BackgroundUpdateHandler:
 
 
 class _BackgroundUpdateContextManager:
-    BACKGROUND_UPDATE_INTERVAL_MS = 1000
-    BACKGROUND_UPDATE_DURATION_MS = 100
-
-    def __init__(self, sleep: bool, clock: Clock):
+    def __init__(
+        self, sleep: bool, clock: Clock, sleep_duration_ms: int, update_duration: int
+    ):
         self._sleep = sleep
         self._clock = clock
+        self._sleep_duration_ms = sleep_duration_ms
+        self._update_duration_ms = update_duration
 
     async def __aenter__(self) -> int:
         if self._sleep:
-            await self._clock.sleep(self.BACKGROUND_UPDATE_INTERVAL_MS / 1000)
+            await self._clock.sleep(self._sleep_duration_ms / 1000)
 
-        return self.BACKGROUND_UPDATE_DURATION_MS
+        return self._update_duration_ms
 
     async def __aexit__(self, *exc) -> None:
         pass
@@ -133,9 +134,6 @@ class BackgroundUpdater:
     process and autotuning the batch size.
     """
 
-    MINIMUM_BACKGROUND_BATCH_SIZE = 1
-    DEFAULT_BACKGROUND_BATCH_SIZE = 100
-
     def __init__(self, hs: "HomeServer", database: "DatabasePool"):
         self._clock = hs.get_clock()
         self.db_pool = database
@@ -160,6 +158,14 @@ class BackgroundUpdater:
         # enable/disable background updates via the admin API.
         self.enabled = True
 
+        self.minimum_background_batch_size = hs.config.background_updates.min_batch_size
+        self.default_background_batch_size = (
+            hs.config.background_updates.default_batch_size
+        )
+        self.update_duration_ms = hs.config.background_updates.update_duration_ms
+        self.sleep_duration_ms = hs.config.background_updates.sleep_duration_ms
+        self.sleep_enabled = hs.config.background_updates.sleep_enabled
+
     def register_update_controller_callbacks(
         self,
         on_update: ON_UPDATE_CALLBACK,
@@ -216,7 +222,9 @@ class BackgroundUpdater:
         if self._on_update_callback is not None:
             return self._on_update_callback(update_name, database_name, oneshot)
 
-        return _BackgroundUpdateContextManager(sleep, self._clock)
+        return _BackgroundUpdateContextManager(
+            sleep, self._clock, self.sleep_duration_ms, self.update_duration_ms
+        )
 
     async def _default_batch_size(self, update_name: str, database_name: str) -> int:
         """The batch size to use for the first iteration of a new background
@@ -225,7 +233,7 @@ class BackgroundUpdater:
         if self._default_batch_size_callback is not None:
             return await self._default_batch_size_callback(update_name, database_name)
 
-        return self.DEFAULT_BACKGROUND_BATCH_SIZE
+        return self.default_background_batch_size
 
     async def _min_batch_size(self, update_name: str, database_name: str) -> int:
         """A lower bound on the batch size of a new background update.
@@ -235,7 +243,7 @@ class BackgroundUpdater:
         if self._min_batch_size_callback is not None:
             return await self._min_batch_size_callback(update_name, database_name)
 
-        return self.MINIMUM_BACKGROUND_BATCH_SIZE
+        return self.minimum_background_batch_size
 
     def get_current_update(self) -> Optional[BackgroundUpdatePerformance]:
         """Returns the current background update, if any."""
@@ -254,9 +262,12 @@ class BackgroundUpdater:
         if self.enabled:
             # if we start a new background update, not all updates are done.
             self._all_done = False
-            run_as_background_process("background_updates", self.run_background_updates)
+            sleep = self.sleep_enabled
+            run_as_background_process(
+                "background_updates", self.run_background_updates, sleep
+            )
 
-    async def run_background_updates(self, sleep: bool = True) -> None:
+    async def run_background_updates(self, sleep: bool) -> None:
         if self._running or not self.enabled:
             return