Allow background tasks to be run on a separate worker.

changelog.d/8369.feature

@@ -0,0 +1 @@
+Allow running background tasks in a separate worker process.

docs/sample_config.yaml

@@ -2484,6 +2484,11 @@ opentracing:
 #  events: worker1
 #  typing: worker1
 
+# The worker that is used to run background tasks (e.g. cleaning up expired
+# data). If not provided this defaults to the main process.
+#
+#run_background_tasks_on: worker1
+
 
 # Configuration for Redis when using workers. This *must* be enabled when
 # using workers (unless using old style direct TCP configuration).

docs/workers.md

@@ -319,6 +319,23 @@ stream_writers:
     events: event_persister1
 ```
 
+#### Background tasks
+
+There is also *experimental* support for moving background tasks to a separate
+worker. Background tasks are run periodically or started via replication. Exactly
+which tasks are configured to run depends on your Synapse configuration (e.g. if
+stats is enabled).
+
+To enable this, the worker must have a `worker_name` and can be configured to run
+background tasks. For example, to move background tasks to a dedicated worker,
+the shared configuration would include:
+
+```yaml
+run_background_tasks_on: background_worker
+```
+
+You might also wish to investigate the `update_user_directory` and
+`media_instance_running_background_jobs` settings.
 
 ### `synapse.app.pusher`
 

synapse/app/_base.py

@@ -28,6 +28,7 @@
 
 import synapse
 from synapse.app import check_bind_error
+from synapse.app.phone_stats_home import start_phone_stats_home
 from synapse.config.server import ListenerConfig
 from synapse.crypto import context_factory
 from synapse.logging.context import PreserveLoggingContext
@@ -274,6 +275,11 @@ def handle_sighup(*args, **kwargs):
         setup_sentry(hs)
         setup_sdnotify(hs)
 
+        # If background tasks are running on the main process, start collecting the
+        # phone home stats.
+        if hs.config.run_background_tasks:
+            start_phone_stats_home(hs)
+
         # We now freeze all allocated objects in the hopes that (almost)
         # everything currently allocated are things that will be used for the
         # rest of time. Doing so means less work each GC (hopefully).

synapse/app/admin_cmd.py

@@ -208,6 +208,7 @@ def start(config_options):
 
     # Explicitly disable background processes
     config.update_user_directory = False
+    config.run_background_tasks = False
     config.start_pushers = False
     config.send_federation = False
 

synapse/app/generic_worker.py

@@ -128,11 +128,13 @@
 from synapse.server import HomeServer, cache_in_self
 from synapse.storage.databases.main.censor_events import CensorEventsStore
 from synapse.storage.databases.main.media_repository import MediaRepositoryStore
+from synapse.storage.databases.main.metrics import ServerMetricsStore
 from synapse.storage.databases.main.monthly_active_users import (
     MonthlyActiveUsersWorkerStore,
 )
 from synapse.storage.databases.main.presence import UserPresenceState
 from synapse.storage.databases.main.search import SearchWorkerStore
+from synapse.storage.databases.main.stats import StatsStore
 from synapse.storage.databases.main.ui_auth import UIAuthWorkerStore
 from synapse.storage.databases.main.user_directory import UserDirectoryStore
 from synapse.types import ReadReceipt
@@ -454,6 +456,7 @@ class GenericWorkerSlavedStore(
     # FIXME(#3714): We need to add UserDirectoryStore as we write directly
     # rather than going via the correct worker.
     UserDirectoryStore,
+    StatsStore,
     UIAuthWorkerStore,
     SlavedDeviceInboxStore,
     SlavedDeviceStore,
@@ -476,6 +479,7 @@ class GenericWorkerSlavedStore(
     SlavedFilteringStore,
     MonthlyActiveUsersWorkerStore,
     MediaRepositoryStore,
+    ServerMetricsStore,
     SearchWorkerStore,
     BaseSlavedStore,
 ):

synapse/app/homeserver.py

@@ -17,14 +17,10 @@
 
 import gc
 import logging
-import math
 import os
-import resource
 import sys
 from typing import Iterable
 
-from prometheus_client import Gauge
-
 from twisted.application import service
 from twisted.internet import defer, reactor
 from twisted.python.failure import Failure
@@ -60,7 +56,6 @@
 from synapse.http.site import SynapseSite
 from synapse.logging.context import LoggingContext
 from synapse.metrics import METRICS_PREFIX, MetricsResource, RegistryProxy
-from synapse.metrics.background_process_metrics import run_as_background_process
 from synapse.module_api import ModuleApi
 from synapse.python_dependencies import check_requirements
 from synapse.replication.http import REPLICATION_PREFIX, ReplicationRestResource
@@ -334,20 +329,6 @@ def start_listening(self, listeners: Iterable[ListenerConfig]):
                 logger.warning("Unrecognized listener type: %s", listener.type)
 
 
-# Gauges to expose monthly active user control metrics
-current_mau_gauge = Gauge("synapse_admin_mau:current", "Current MAU")
-current_mau_by_service_gauge = Gauge(
-    "synapse_admin_mau_current_mau_by_service",
-    "Current MAU by service",
-    ["app_service"],
-)
-max_mau_gauge = Gauge("synapse_admin_mau:max", "MAU Limit")
-registered_reserved_users_mau_gauge = Gauge(
-    "synapse_admin_mau:registered_reserved_users",
-    "Registered users with reserved threepids",
-)
-
-
 def setup(config_options):
     """
     Args:
@@ -389,8 +370,6 @@ def setup(config_options):
     except UpgradeDatabaseException as e:
         quit_with_error("Failed to upgrade database: %s" % (e,))
 
-    hs.setup_master()
-
     async def do_acme() -> bool:
         """
         Reprovision an ACME certificate, if it's required.
@@ -486,92 +465,6 @@ def stopService(self):
         return self._port.stopListening()
 
 
-# Contains the list of processes we will be monitoring
-# currently either 0 or 1
-_stats_process = []
-
-
-async def phone_stats_home(hs, stats, stats_process=_stats_process):
-    logger.info("Gathering stats for reporting")
-    now = int(hs.get_clock().time())
-    uptime = int(now - hs.start_time)
-    if uptime < 0:
-        uptime = 0
-
-    #
-    # Performance statistics. Keep this early in the function to maintain reliability of `test_performance_100` test.
-    #
-    old = stats_process[0]
-    new = (now, resource.getrusage(resource.RUSAGE_SELF))
-    stats_process[0] = new
-
-    # Get RSS in bytes
-    stats["memory_rss"] = new[1].ru_maxrss
-
-    # Get CPU time in % of a single core, not % of all cores
-    used_cpu_time = (new[1].ru_utime + new[1].ru_stime) - (
-        old[1].ru_utime + old[1].ru_stime
-    )
-    if used_cpu_time == 0 or new[0] == old[0]:
-        stats["cpu_average"] = 0
-    else:
-        stats["cpu_average"] = math.floor(used_cpu_time / (new[0] - old[0]) * 100)
-
-    #
-    # General statistics
-    #
-
-    stats["homeserver"] = hs.config.server_name
-    stats["server_context"] = hs.config.server_context
-    stats["timestamp"] = now
-    stats["uptime_seconds"] = uptime
-    version = sys.version_info
-    stats["python_version"] = "{}.{}.{}".format(
-        version.major, version.minor, version.micro
-    )
-    stats["total_users"] = await hs.get_datastore().count_all_users()
-
-    total_nonbridged_users = await hs.get_datastore().count_nonbridged_users()
-    stats["total_nonbridged_users"] = total_nonbridged_users
-
-    daily_user_type_results = await hs.get_datastore().count_daily_user_type()
-    for name, count in daily_user_type_results.items():
-        stats["daily_user_type_" + name] = count
-
-    room_count = await hs.get_datastore().get_room_count()
-    stats["total_room_count"] = room_count
-
-    stats["daily_active_users"] = await hs.get_datastore().count_daily_users()
-    stats["monthly_active_users"] = await hs.get_datastore().count_monthly_users()
-    stats["daily_active_rooms"] = await hs.get_datastore().count_daily_active_rooms()
-    stats["daily_messages"] = await hs.get_datastore().count_daily_messages()
-
-    r30_results = await hs.get_datastore().count_r30_users()
-    for name, count in r30_results.items():
-        stats["r30_users_" + name] = count
-
-    daily_sent_messages = await hs.get_datastore().count_daily_sent_messages()
-    stats["daily_sent_messages"] = daily_sent_messages
-    stats["cache_factor"] = hs.config.caches.global_factor
-    stats["event_cache_size"] = hs.config.caches.event_cache_size
-
-    #
-    # Database version
-    #
-
-    # This only reports info about the *main* database.
-    stats["database_engine"] = hs.get_datastore().db_pool.engine.module.__name__
-    stats["database_server_version"] = hs.get_datastore().db_pool.engine.server_version
-
-    logger.info("Reporting stats to %s: %s" % (hs.config.report_stats_endpoint, stats))
-    try:
-        await hs.get_proxied_http_client().put_json(
-            hs.config.report_stats_endpoint, stats
-        )
-    except Exception as e:
-        logger.warning("Error reporting stats: %s", e)
-
-
 def run(hs):
     PROFILE_SYNAPSE = False
     if PROFILE_SYNAPSE:
@@ -597,81 +490,6 @@ def profiled(*args, **kargs):
         ThreadPool._worker = profile(ThreadPool._worker)
         reactor.run = profile(reactor.run)
 
-    clock = hs.get_clock()
-
-    stats = {}
-
-    def performance_stats_init():
-        _stats_process.clear()
-        _stats_process.append(
-            (int(hs.get_clock().time()), resource.getrusage(resource.RUSAGE_SELF))
-        )
-
-    def start_phone_stats_home():
-        return run_as_background_process(
-            "phone_stats_home", phone_stats_home, hs, stats
-        )
-
-    def generate_user_daily_visit_stats():
-        return run_as_background_process(
-            "generate_user_daily_visits", hs.get_datastore().generate_user_daily_visits
-        )
-
-    # Rather than update on per session basis, batch up the requests.
-    # If you increase the loop period, the accuracy of user_daily_visits
-    # table will decrease
-    clock.looping_call(generate_user_daily_visit_stats, 5 * 60 * 1000)
-
-    # monthly active user limiting functionality
-    def reap_monthly_active_users():
-        return run_as_background_process(
-            "reap_monthly_active_users", hs.get_datastore().reap_monthly_active_users
-        )
-
-    clock.looping_call(reap_monthly_active_users, 1000 * 60 * 60)
-    reap_monthly_active_users()
-
-    async def generate_monthly_active_users():
-        current_mau_count = 0
-        current_mau_count_by_service = {}
-        reserved_users = ()
-        store = hs.get_datastore()
-        if hs.config.limit_usage_by_mau or hs.config.mau_stats_only:
-            current_mau_count = await store.get_monthly_active_count()
-            current_mau_count_by_service = (
-                await store.get_monthly_active_count_by_service()
-            )
-            reserved_users = await store.get_registered_reserved_users()
-        current_mau_gauge.set(float(current_mau_count))
-
-        for app_service, count in current_mau_count_by_service.items():
-            current_mau_by_service_gauge.labels(app_service).set(float(count))
-
-        registered_reserved_users_mau_gauge.set(float(len(reserved_users)))
-        max_mau_gauge.set(float(hs.config.max_mau_value))
-
-    def start_generate_monthly_active_users():
-        return run_as_background_process(
-            "generate_monthly_active_users", generate_monthly_active_users
-        )
-
-    start_generate_monthly_active_users()
-    if hs.config.limit_usage_by_mau or hs.config.mau_stats_only:
-        clock.looping_call(start_generate_monthly_active_users, 5 * 60 * 1000)
-    # End of monthly active user settings
-
-    if hs.config.report_stats:
-        logger.info("Scheduling stats reporting for 3 hour intervals")
-        clock.looping_call(start_phone_stats_home, 3 * 60 * 60 * 1000)
-
-        # We need to defer this init for the cases that we daemonize
-        # otherwise the process ID we get is that of the non-daemon process
-        clock.call_later(0, performance_stats_init)
-
-        # We wait 5 minutes to send the first set of stats as the server can
-        # be quite busy the first few minutes
-        clock.call_later(5 * 60, start_phone_stats_home)
-
     _base.start_reactor(
         "synapse-homeserver",
         soft_file_limit=hs.config.soft_file_limit,