summary refs log tree commit diff
path: root/synapse/util/caches/lrucache.py
diff options
context:
space:
mode:
authorErik Johnston <erikj@jki.re>2018-03-19 11:44:26 +0000
committerGitHub <noreply@github.com>2018-03-19 11:44:26 +0000
commit3f961e638a1424ae5c6310fbec405bf3eb7b8acf (patch)
tree4bffcb30e63645752056e5233ff6521401cdec03 /synapse/util/caches/lrucache.py
parentMerge branch 'master' of github.com:matrix-org/synapse into develop (diff)
parentAdd comments (diff)
downloadsynapse-3f961e638a1424ae5c6310fbec405bf3eb7b8acf.tar.xz
Merge pull request #3005 from matrix-org/erikj/fix_cache_size
Fix bug where state cache used lots of memory
Diffstat (limited to 'synapse/util/caches/lrucache.py')
-rw-r--r--synapse/util/caches/lrucache.py15
1 files changed, 11 insertions, 4 deletions
diff --git a/synapse/util/caches/lrucache.py b/synapse/util/caches/lrucache.py
index f088dd430e..1c5a982094 100644
--- a/synapse/util/caches/lrucache.py
+++ b/synapse/util/caches/lrucache.py
@@ -154,14 +154,21 @@ class LruCache(object):
         def cache_set(key, value, callbacks=[]):
             node = cache.get(key, None)
             if node is not None:
-                if value != node.value:
+                # We sometimes store large objects, e.g. dicts, which cause
+                # the inequality check to take a long time. So let's only do
+                # the check if we have some callbacks to call.
+                if node.callbacks and value != node.value:
                     for cb in node.callbacks:
                         cb()
                     node.callbacks.clear()
 
-                    if size_callback:
-                        cached_cache_len[0] -= size_callback(node.value)
-                        cached_cache_len[0] += size_callback(value)
+                # We don't bother to protect this by value != node.value as
+                # generally size_callback will be cheap compared with equality
+                # checks. (For example, taking the size of two dicts is quicker
+                # than comparing them for equality.)
+                if size_callback:
+                    cached_cache_len[0] -= size_callback(node.value)
+                    cached_cache_len[0] += size_callback(value)
 
                 node.callbacks.update(callbacks)