From 547b1355d3747b267db3e21aefd143382f49f4ec Mon Sep 17 00:00:00 2001 From: Erik Johnston Date: Tue, 17 Jul 2018 10:27:51 +0100 Subject: [PATCH] Fix perf regression in PR #3530 The get_entities_changed function was changed to return all changed entities since the given stream position, rather than only those changed from a given list of entities. This resulted in the function incorrectly returning large numbers of entities that, for example, caused large increases in database usage. --- synapse/util/caches/stream_change_cache.py | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/synapse/util/caches/stream_change_cache.py b/synapse/util/caches/stream_change_cache.py index 258655349..c1e76b1a0 100644 --- a/synapse/util/caches/stream_change_cache.py +++ b/synapse/util/caches/stream_change_cache.py @@ -74,12 +74,17 @@ class StreamChangeCache(object): assert type(stream_pos) is int if stream_pos >= self._earliest_known_stream_pos: - result = { + changed_entities = { self._cache[k] for k in self._cache.islice( start=self._cache.bisect_right(stream_pos), ) } + result = { + e for e in entities + if e in changed_entities + } + self.metrics.inc_hits() else: result = set(entities)