diff --git a/synapse/config/database.py b/synapse/config/database.py
index 3d7d92f615..651e31b576 100644
--- a/synapse/config/database.py
+++ b/synapse/config/database.py
@@ -33,6 +33,9 @@ DEFAULT_CONFIG = """\
# 'name' gives the database engine to use: either 'sqlite3' (for SQLite) or
# 'psycopg2' (for PostgreSQL).
#
+# 'txn_limit' gives the maximum number of transactions to run per connection
+# before reconnecting. Defaults to 0, which means no limit.
+#
# 'args' gives options which are passed through to the database engine,
# except for options starting 'cp_', which are used to configure the Twisted
# connection pool. For a reference to valid arguments, see:
@@ -53,6 +56,7 @@ DEFAULT_CONFIG = """\
#
#database:
# name: psycopg2
+# txn_limit: 10000
# args:
# user: synapse_user
# password: secretpassword
diff --git a/synapse/storage/database.py b/synapse/storage/database.py
index 4d4643619f..c8015a3848 100644
--- a/synapse/storage/database.py
+++ b/synapse/storage/database.py
@@ -15,6 +15,7 @@
# limitations under the License.
import logging
import time
+from collections import defaultdict
from sys import intern
from time import monotonic as monotonic_time
from typing import (
@@ -397,6 +398,7 @@ class DatabasePool:
):
self.hs = hs
self._clock = hs.get_clock()
+ self._txn_limit = database_config.config.get("txn_limit", 0)
self._database_config = database_config
self._db_pool = make_pool(hs.get_reactor(), database_config, engine)
@@ -406,6 +408,9 @@ class DatabasePool:
self._current_txn_total_time = 0.0
self._previous_loop_ts = 0.0
+ # Transaction counter: key is the twisted thread id, value is the current count
+ self._txn_counters: Dict[int, int] = defaultdict(int)
+
# TODO(paul): These can eventually be removed once the metrics code
# is running in mainline, and we have some nice monitoring frontends
# to watch it
@@ -750,10 +755,26 @@ class DatabasePool:
sql_scheduling_timer.observe(sched_duration_sec)
context.add_database_scheduled(sched_duration_sec)
+ if self._txn_limit > 0:
+ tid = self._db_pool.threadID()
+ self._txn_counters[tid] += 1
+
+ if self._txn_counters[tid] > self._txn_limit:
+ logger.debug(
+ "Reconnecting database connection over transaction limit"
+ )
+ conn.reconnect()
+ opentracing.log_kv(
+ {"message": "reconnected due to txn limit"}
+ )
+ self._txn_counters[tid] = 1
+
if self.engine.is_connection_closed(conn):
logger.debug("Reconnecting closed database connection")
conn.reconnect()
opentracing.log_kv({"message": "reconnected"})
+ if self._txn_limit > 0:
+ self._txn_counters[tid] = 1
try:
if db_autocommit:
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