1 files changed, 0 insertions, 12 deletions
diff --git a/synapse/handlers/e2e_keys.py b/synapse/handlers/e2e_keys.py
index 739653a3fa..92b18378fc 100644
--- a/synapse/handlers/e2e_keys.py
+++ b/synapse/handlers/e2e_keys.py
@@ -38,7 +38,6 @@ from synapse.types import (
 )
 from synapse.util import json_decoder, unwrapFirstError
 from synapse.util.async_helpers import Linearizer
-from synapse.util.caches.expiringcache import ExpiringCache
 from synapse.util.retryutils import NotRetryingDestination
 
 if TYPE_CHECKING:
@@ -1292,17 +1291,6 @@ class SigningKeyEduUpdater:
         # user_id -> list of updates waiting to be handled.
         self._pending_updates = {}  # type: Dict[str, List[Tuple[JsonDict, JsonDict]]]
 
-        # Recently seen stream ids. We don't bother keeping these in the DB,
-        # but they're useful to have them about to reduce the number of spurious
-        # resyncs.
-        self._seen_updates = ExpiringCache(
-            cache_name="signing_key_update_edu",
-            clock=self.clock,
-            max_len=10000,
-            expiry_ms=30 * 60 * 1000,
-            iterable=True,
-        )
-
     async def incoming_signing_key_update(
         self, origin: str, edu_content: JsonDict
     ) -> None: