From 20fa83f3744b25e513fdc904261c87c324bbc87e Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Wed, 14 Oct 2020 15:40:06 +0100
Subject: [PATCH] Remove racey assertion in MultiWriterIDGenerator (#8530)
We asserted that the IDs returned by postgres sequence was greater than
any we had seen, however this is technically racey as we may update the
current positions out of order.
We now assert that the sequences are correct on startup, so the
assertion is no longer really required, so we remove them.
---
changelog.d/8530.bugfix | 1 +
synapse/storage/util/id_generators.py | 7 -------
2 files changed, 1 insertion(+), 7 deletions(-)
create mode 100644 changelog.d/8530.bugfix
diff --git a/changelog.d/8530.bugfix b/changelog.d/8530.bugfix
new file mode 100644
index 0000000000..443d88424e
--- /dev/null
+++ b/changelog.d/8530.bugfix
@@ -0,0 +1 @@
+Fix rare bug where sending an event would fail due to a racey assertion.
diff --git a/synapse/storage/util/id_generators.py b/synapse/storage/util/id_generators.py
index ad017207aa..eccd2d5b7b 100644
--- a/synapse/storage/util/id_generators.py
+++ b/synapse/storage/util/id_generators.py
@@ -612,14 +612,7 @@ class _MultiWriterCtxManager:
db_autocommit=True,
)
- # Assert the fetched ID is actually greater than any ID we've already
- # seen. If not, then the sequence and table have got out of sync
- # somehow.
with self.id_gen._lock:
- assert max(self.id_gen._current_positions.values(), default=0) < min(
- self.stream_ids
- )
-
self.id_gen._unfinished_ids.update(self.stream_ids)
if self.multiple_ids is None:
--
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