From f8bf83b811cf54b4ce668bcda6043d14c4980f00 Mon Sep 17 00:00:00 2001
From: Sean <squahtx@users.noreply.github.com>
Date: Wed, 1 Sep 2021 11:55:31 +0100
Subject: [PATCH] Skip the final GC on shutdown to improve restart times
(#10712)
Use `gc.freeze()` on exit to exclude all existing objects from the final GC.
In testing, this sped up shutdown by up to a few seconds.
`gc.freeze()` runs in constant time, so there is little chance of performance
regression.
Signed-off-by: Sean Quah <seanq@element.io>
---
changelog.d/10712.feature | 1 +
synapse/app/_base.py | 7 +++++++
2 files changed, 8 insertions(+)
create mode 100644 changelog.d/10712.feature
diff --git a/changelog.d/10712.feature b/changelog.d/10712.feature
new file mode 100644
index 0000000000..d04db6f26f
--- /dev/null
+++ b/changelog.d/10712.feature
@@ -0,0 +1 @@
+Skip final GC at shutdown to improve restart performance.
diff --git a/synapse/app/_base.py b/synapse/app/_base.py
index 39e28aff9f..6fc14930d1 100644
--- a/synapse/app/_base.py
+++ b/synapse/app/_base.py
@@ -12,6 +12,7 @@
# 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.
+import atexit
import gc
import logging
import os
@@ -403,6 +404,12 @@ async def start(hs: "HomeServer"):
gc.collect()
gc.freeze()
+ # Speed up shutdowns by freezing all allocated objects. This moves everything
+ # into the permanent generation and excludes them from the final GC.
+ # Unfortunately only works on Python 3.7
+ if platform.python_implementation() == "CPython" and sys.version_info >= (3, 7):
+ atexit.register(gc.freeze)
+
def setup_sentry(hs):
"""Enable sentry integration, if enabled in configuration
--
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