1 files changed, 69 insertions, 0 deletions
diff --git a/lib/gitlab/sidekiq_middleware/memory_killer.rb b/lib/gitlab/sidekiq_middleware/memory_killer.rb
new file mode 100644
index 00000000000..47333d257eb
--- /dev/null
+++ b/lib/gitlab/sidekiq_middleware/memory_killer.rb
@@ -0,0 +1,69 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module SidekiqMiddleware
+    class MemoryKiller
+      # Default the RSS limit to 0, meaning the MemoryKiller is disabled
+      MAX_RSS = (ENV['SIDEKIQ_MEMORY_KILLER_MAX_RSS'] || 0).to_s.to_i
+      # Give Sidekiq 15 minutes of grace time after exceeding the RSS limit
+      GRACE_TIME = (ENV['SIDEKIQ_MEMORY_KILLER_GRACE_TIME'] || 15 * 60).to_s.to_i
+      # Wait 30 seconds for running jobs to finish during graceful shutdown
+      SHUTDOWN_WAIT = (ENV['SIDEKIQ_MEMORY_KILLER_SHUTDOWN_WAIT'] || 30).to_s.to_i
+
+      # Create a mutex used to ensure there will be only one thread waiting to
+      # shut Sidekiq down
+      MUTEX = Mutex.new
+
+      def call(worker, job, queue)
+        yield
+
+        current_rss = get_rss
+
+        return unless MAX_RSS > 0 && current_rss > MAX_RSS
+
+        Thread.new do
+          # Return if another thread is already waiting to shut Sidekiq down
+          next unless MUTEX.try_lock
+
+          Sidekiq.logger.warn "Sidekiq worker PID-#{pid} current RSS #{current_rss}"\
+            " exceeds maximum RSS #{MAX_RSS} after finishing job #{worker.class} JID-#{job['jid']}"
+          Sidekiq.logger.warn "Sidekiq worker PID-#{pid} will stop fetching new jobs in #{GRACE_TIME} seconds, and will be shut down #{SHUTDOWN_WAIT} seconds later"
+
+          # Wait `GRACE_TIME` to give the memory intensive job time to finish.
+          # Then, tell Sidekiq to stop fetching new jobs.
+          wait_and_signal(GRACE_TIME, 'SIGTSTP', 'stop fetching new jobs')
+
+          # Wait `SHUTDOWN_WAIT` to give already fetched jobs time to finish.
+          # Then, tell Sidekiq to gracefully shut down by giving jobs a few more
+          # moments to finish, killing and requeuing them if they didn't, and
+          # then terminating itself.
+          wait_and_signal(SHUTDOWN_WAIT, 'SIGTERM', 'gracefully shut down')
+
+          # Wait for Sidekiq to shutdown gracefully, and kill it if it didn't.
+          wait_and_signal(Sidekiq.options[:timeout] + 2, 'SIGKILL', 'die')
+        end
+      end
+
+      private
+
+      def get_rss
+        output, status = Gitlab::Popen.popen(%W(ps -o rss= -p #{pid}), Rails.root.to_s)
+        return 0 unless status.zero?
+
+        output.to_i
+      end
+
+      def wait_and_signal(time, signal, explanation)
+        Sidekiq.logger.warn "waiting #{time} seconds before sending Sidekiq worker PID-#{pid} #{signal} (#{explanation})"
+        sleep(time)
+
+        Sidekiq.logger.warn "sending Sidekiq worker PID-#{pid} #{signal} (#{explanation})"
+        Process.kill(signal, pid)
+      end
+
+      def pid
+        Process.pid
+      end
+    end
+  end
+end