Force with_fast_statement_timeout to use replicas

app/models/application_record.rb

@@ -52,11 +52,13 @@ class ApplicationRecord < ActiveRecord::Base
 
   # Start a new transaction with a shorter-than-usual statement timeout. This is
   # currently one third of the default 15-second timeout
-  def self.with_fast_statement_timeout
-    transaction(requires_new: true) do
-      connection.exec_query("SET LOCAL statement_timeout = 5000")
+  def self.with_fast_read_statement_timeout
+    ::Gitlab::Database::LoadBalancing::Session.current.use_replica do
+      transaction(requires_new: true) do
+        connection.exec_query("SET LOCAL statement_timeout = 5000")
 
-      yield
+        yield
+      end
     end
   end
 

lib/gitlab/issuables_count_for_state.rb

@@ -78,7 +78,7 @@ module Gitlab
       # to perform the calculation more efficiently. Until then, use a shorter
       # timeout and return -1 as a sentinel value if it is triggered
       begin
-        ApplicationRecord.with_fast_statement_timeout do
+        ApplicationRecord.with_fast_read_statement_timeout do
           finder.count_by_state
         end
       rescue ActiveRecord::QueryCanceled => err