From e67e530a14e25f3e8011681ae887cf4b52bafd11 Mon Sep 17 00:00:00 2001
From: Eric Eastwood <erice@element.io>
Date: Fri, 6 Feb 2026 12:44:29 -0600
Subject: [PATCH 1/2] Log if we ever `gc.freeze()`

---
 synapse/app/_base.py | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/synapse/app/_base.py b/synapse/app/_base.py
index c64c41e9d27..7f4855f36bd 100644
--- a/synapse/app/_base.py
+++ b/synapse/app/_base.py
@@ -776,6 +776,11 @@ def log_shutdown() -> None:
         #
         # PyPy does not (yet?) implement gc.freeze()
         if hasattr(gc, "freeze"):
+            logger.info(
+                "garbage collector: Freezing all allocated objects in the hopes that (almost) "
+                "everything currently allocated are things that will be used by the homeserver "
+                "for the rest of time. Doing so means less work each GC (hopefully)."
+            )
             gc.collect()
             gc.freeze()
 

From 07d791df64fd22575bcb13c0807eb635399bb8b9 Mon Sep 17 00:00:00 2001
From: Eric Eastwood <erice@element.io>
Date: Fri, 6 Feb 2026 12:50:25 -0600
Subject: [PATCH 2/2] Add changelog

---
 changelog.d/19440.misc | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 changelog.d/19440.misc

diff --git a/changelog.d/19440.misc b/changelog.d/19440.misc
new file mode 100644
index 00000000000..77776011144
--- /dev/null
+++ b/changelog.d/19440.misc
@@ -0,0 +1 @@
+Add log to explain when and why we freeze objects in the garbage collector.