Merge pull request #3745 from DataDog/anmarchenko/fix_telemetry_threa…

…ds_deadlock_backport

fix telemetry threads deadlock backport

lib/datadog/core/telemetry/worker.rb

@@ -52,8 +52,6 @@ def start
         def stop(force_stop = false, timeout = @shutdown_timeout)
           buffer.close if running?
 
-          flush_events(dequeue) if work_pending?
-
           super
         end
 
@@ -136,6 +134,10 @@ def dequeue
           buffer.pop
         end
 
+        def work_pending?
+          run_loop? || !buffer.empty?
+        end
+
         def buffer_klass
           if Core::Environment::Ext::RUBY_ENGINE == 'ruby'
             Core::Buffer::CRuby

spec/datadog/core/telemetry/worker_spec.rb

@@ -275,6 +275,8 @@
       worker.start
 
       expect(worker).to receive(:flush_events).at_least(:once)
+
+      worker.enqueue(Datadog::Core::Telemetry::Event::AppIntegrationsChange.new)
       worker.stop(true)
     end
   end