diff --git a/assets/runtime/config/gitlabhq/unicorn.rb b/assets/runtime/config/gitlabhq/unicorn.rb
index ee8c0cf9..3d62d74d 100644
--- a/assets/runtime/config/gitlabhq/unicorn.rb
+++ b/assets/runtime/config/gitlabhq/unicorn.rb
@@ -120,6 +120,10 @@ after_fork do |server, worker|
   # the following is *required* for Rails + "preload_app true",
   defined?(ActiveRecord::Base) and
     ActiveRecord::Base.establish_connection
+	
+  # reset prometheus client, this will cause any opened metrics files to be closed
+  defined?(::Prometheus::Client.reinitialize_on_pid_change) &&
+    Prometheus::Client.reinitialize_on_pid_change
 
   # if preload_app is true, then you may also want to check and
   # restart any other shared sockets/descriptors such as Memcached,