Run things as background processes

This fixes #3518, and ensures that we get useful logs and metrics for lots of
things that happen in the background.

(There are certainly more things that happen in the background; these are just
the common ones I've found running a single-process synapse locally).

1 files changed, 6 insertions, 4 deletions

diff --git a/synapse/storage/events_worker.py b/synapse/storage/events_worker.py

index 67433606c6..f28239a808 100644
--- a/synapse/storage/events_worker.py
+++ b/synapse/storage/events_worker.py
@@ -25,6 +25,7 @@ from synapse.events import EventBase  # noqa: F401
 from synapse.events import FrozenEvent
 from synapse.events.snapshot import EventContext  # noqa: F401
 from synapse.events.utils import prune_event
+from synapse.metrics.background_process_metrics import run_as_background_process
 from synapse.util.logcontext import (
     LoggingContext,
     PreserveLoggingContext,
@@ -322,10 +323,11 @@ class EventsWorkerStore(SQLBaseStore):
                 should_start = False
 
         if should_start:
-            with PreserveLoggingContext():
-                self.runWithConnection(
-                    self._do_fetch
-                )
+            run_as_background_process(
+                "fetch_events",
+                self.runWithConnection,
+                self._do_fetch,
+            )
 
         logger.debug("Loading %d events", len(events))
         with PreserveLoggingContext():