1 files changed, 20 insertions, 16 deletions
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb b/activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb
index 7eab7de5d3..e53ba4e666 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb
@@ -83,7 +83,9 @@ module ActiveRecord
       # the same SQL query and repeatedly return the same result each time, silently
       # undermining the randomness you were expecting.
       def clear_query_cache
-        @query_cache.clear
+        @lock.synchronize do
+          @query_cache.clear
+        end
       end
 
       def select_all(arel, name = nil, binds = [], preparable: nil)
@@ -99,21 +101,23 @@ module ActiveRecord
       private
 
         def cache_sql(sql, name, binds)
-          result =
-            if @query_cache[sql].key?(binds)
-              ActiveSupport::Notifications.instrument(
-                "sql.active_record",
-                sql: sql,
-                binds: binds,
-                name: name,
-                connection_id: object_id,
-                cached: true,
-              )
-              @query_cache[sql][binds]
-            else
-              @query_cache[sql][binds] = yield
-            end
-          result.dup
+          @lock.synchronize do
+            result =
+              if @query_cache[sql].key?(binds)
+                ActiveSupport::Notifications.instrument(
+                  "sql.active_record",
+                  sql: sql,
+                  binds: binds,
+                  name: name,
+                  connection_id: object_id,
+                  cached: true,
+                )
+                @query_cache[sql][binds]
+              else
+                @query_cache[sql][binds] = yield
+              end
+            result.dup
+          end
         end
 
         # If arel is locked this is a SELECT ... FOR UPDATE or somesuch. Such