From 42d47e0268ab57c99d82b03b90f8ff1f14a13e98 Mon Sep 17 00:00:00 2001
From: Aleksei Lipniagov <alipniagov@gitlab.com>
Date: Fri, 13 Sep 2019 12:44:08 +0300
Subject: [PATCH] Reinitialize samplers on restart

---
 config/initializers/7_prometheus_metrics.rb | 4 ++--
 lib/gitlab/daemon.rb                        | 8 ++++++++
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/config/initializers/7_prometheus_metrics.rb b/config/initializers/7_prometheus_metrics.rb
index 143b34b5368..24df2b0b70b 100644
--- a/config/initializers/7_prometheus_metrics.rb
+++ b/config/initializers/7_prometheus_metrics.rb
@@ -48,9 +48,9 @@ if !Rails.env.test? && Gitlab::Metrics.prometheus_metrics_enabled?
 
   Gitlab::Cluster::LifecycleEvents.on_master_start do
     if defined?(::Unicorn)
-      Gitlab::Metrics::Samplers::UnicornSampler.initialize_instance(Settings.monitoring.unicorn_sampler_interval).start
+      Gitlab::Metrics::Samplers::UnicornSampler.reinitialize_instance(Settings.monitoring.unicorn_sampler_interval).start
     elsif defined?(::Puma)
-      Gitlab::Metrics::Samplers::PumaSampler.initialize_instance(Settings.monitoring.puma_sampler_interval).start
+      Gitlab::Metrics::Samplers::PumaSampler.reinitialize_instance(Settings.monitoring.puma_sampler_interval).start
     end
   end
 end
diff --git a/lib/gitlab/daemon.rb b/lib/gitlab/daemon.rb
index 2f4ae010e74..90a96e365e8 100644
--- a/lib/gitlab/daemon.rb
+++ b/lib/gitlab/daemon.rb
@@ -10,6 +10,14 @@ module Gitlab
       @instance
     end
 
+    def self.reinitialize_instance(*args)
+      @instance.stop if @instance
+
+      @instance = new(*args)
+      Kernel.at_exit(&@instance.method(:stop))
+      @instance
+    end
+
     def self.instance
       @instance ||= initialize_instance
     end
-- 
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