Merge branch 'add-sidekiq-memory-killer-metrics-prometheus' into 'master'

Add Sidekiq memory killer prometheus metrics

See merge request gitlab-org/gitlab!17994

lib/gitlab/sidekiq_daemon/memory_killer.rb

@@ -21,14 +21,46 @@ module Gitlab
       # In case not set, default to 300M. This is for extra-safe.
       DEFAULT_MAX_MEMORY_GROWTH_KB = 300_000
 
+      # Phases of memory killer
+      PHASE = {
+        running: 1,
+        above_soft_limit: 2,
+        stop_fetching_new_jobs: 3,
+        shutting_down: 4,
+        killing_sidekiq: 5
+      }.freeze
+
       def initialize
         super
 
         @enabled = true
+        @metrics = init_metrics
       end
 
       private
 
+      def init_metrics
+        {
+          sidekiq_current_rss:                  ::Gitlab::Metrics.gauge(:sidekiq_current_rss, 'Current RSS of Sidekiq Worker'),
+          sidekiq_memory_killer_soft_limit_rss: ::Gitlab::Metrics.gauge(:sidekiq_memory_killer_soft_limit_rss, 'Current soft_limit_rss of Sidekiq Worker'),
+          sidekiq_memory_killer_hard_limit_rss: ::Gitlab::Metrics.gauge(:sidekiq_memory_killer_hard_limit_rss, 'Current hard_limit_rss of Sidekiq Worker'),
+          sidekiq_memory_killer_phase:          ::Gitlab::Metrics.gauge(:sidekiq_memory_killer_phase, 'Current phase of Sidekiq Worker')
+        }
+      end
+
+      def refresh_state(phase)
+        @phase = PHASE.fetch(phase)
+        @current_rss = get_rss
+        @soft_limit_rss = get_soft_limit_rss
+        @hard_limit_rss = get_hard_limit_rss
+
+        # track the current state as prometheus gauges
+        @metrics[:sidekiq_memory_killer_phase].set({}, @phase)
+        @metrics[:sidekiq_current_rss].set({}, @current_rss)
+        @metrics[:sidekiq_memory_killer_soft_limit_rss].set({}, @soft_limit_rss)
+        @metrics[:sidekiq_memory_killer_hard_limit_rss].set({}, @hard_limit_rss)
+      end
+
       def run_thread
         Sidekiq.logger.info(
           class: self.class.to_s,
@@ -77,41 +109,51 @@ module Gitlab
         # Tell Sidekiq to stop fetching new jobs
         # We first SIGNAL and then wait given time
         # We also monitor a number of running jobs and allow to restart early
+        refresh_state(:stop_fetching_new_jobs)
         signal_and_wait(SHUTDOWN_TIMEOUT_SECONDS, 'SIGTSTP', 'stop fetching new jobs')
         return unless enabled?
 
         # Tell sidekiq to restart itself
         # Keep extra safe to wait `Sidekiq.options[:timeout] + 2` seconds before SIGKILL
+        refresh_state(:shutting_down)
         signal_and_wait(Sidekiq.options[:timeout] + 2, 'SIGTERM', 'gracefully shut down')
         return unless enabled?
 
         # Ideally we should never reach this condition
         # Wait for Sidekiq to shutdown gracefully, and kill it if it didn't
         # Kill the whole pgroup, so we can be sure no children are left behind
+        refresh_state(:killing_sidekiq)
         signal_pgroup('SIGKILL', 'die')
       end
 
       def rss_within_range?
-        current_rss = nil
+        refresh_state(:running)
+
         deadline = Gitlab::Metrics::System.monotonic_time + GRACE_BALLOON_SECONDS.seconds
         loop do
           return true unless enabled?
 
-          current_rss = get_rss
-
           # RSS go above hard limit should trigger forcible shutdown right away
-          break if current_rss > hard_limit_rss
+          break if @current_rss > @hard_limit_rss
 
           # RSS go below the soft limit
-          return true if current_rss < soft_limit_rss
+          return true if @current_rss < @soft_limit_rss
 
           # RSS did not go below the soft limit within deadline, restart
           break if Gitlab::Metrics::System.monotonic_time > deadline
 
           sleep(CHECK_INTERVAL_SECONDS)
+
+          refresh_state(:above_soft_limit)
         end
 
-        log_rss_out_of_range(current_rss, hard_limit_rss, soft_limit_rss)
+        # There are two chances to break from loop:
+        #   - above hard limit, or
+        #   - above soft limit after deadline
+        # When `above hard limit`, it immediately go to `stop_fetching_new_jobs`
+        # So ignore `above hard limit` and always set `above_soft_limit` here
+        refresh_state(:above_soft_limit)
+        log_rss_out_of_range(@current_rss, @hard_limit_rss, @soft_limit_rss)
 
         false
       end
@@ -143,11 +185,11 @@ module Gitlab
         output.to_i
       end
 
-      def soft_limit_rss
+      def get_soft_limit_rss
         SOFT_LIMIT_RSS_KB + rss_increase_by_jobs
       end
 
-      def hard_limit_rss
+      def get_hard_limit_rss
         HARD_LIMIT_RSS_KB
       end
 

spec/lib/gitlab/sidekiq_daemon/memory_killer_spec.rb

@@ -7,9 +7,12 @@ describe Gitlab::SidekiqDaemon::MemoryKiller do
   let(:pid) { 12345 }
 
   before do
-    allow(memory_killer).to receive(:pid).and_return(pid)
     allow(Sidekiq.logger).to receive(:info)
     allow(Sidekiq.logger).to receive(:warn)
+    allow(memory_killer).to receive(:pid).and_return(pid)
+
+    # make sleep no-op
+    allow(memory_killer).to receive(:sleep) {}
   end
 
   describe '#run_thread' do
@@ -39,8 +42,9 @@ describe Gitlab::SidekiqDaemon::MemoryKiller do
             pid: pid,
             message: "Exception from run_thread: My Exception")
 
-        expect(memory_killer).to receive(:rss_within_range?).twice.and_raise(StandardError, 'My Exception')
-        expect(memory_killer).to receive(:sleep).twice.with(Gitlab::SidekiqDaemon::MemoryKiller::CHECK_INTERVAL_SECONDS)
+        expect(memory_killer).to receive(:rss_within_range?)
+          .twice
+          .and_raise(StandardError, 'My Exception')
 
         expect { subject }.not_to raise_exception
       end
@@ -52,7 +56,9 @@ describe Gitlab::SidekiqDaemon::MemoryKiller do
             pid: pid,
             message: "Exception from run_thread: My Exception")
 
-        expect(memory_killer).to receive(:rss_within_range?).once.and_raise(Exception, 'My Exception')
+        expect(memory_killer).to receive(:rss_within_range?)
+          .once
+          .and_raise(Exception, 'My Exception')
 
         expect(memory_killer).to receive(:sleep).with(Gitlab::SidekiqDaemon::MemoryKiller::CHECK_INTERVAL_SECONDS)
         expect(Sidekiq.logger).to receive(:warn).once
@@ -78,7 +84,9 @@ describe Gitlab::SidekiqDaemon::MemoryKiller do
     end
 
     it 'not invoke restart_sidekiq when rss in range' do
-      expect(memory_killer).to receive(:rss_within_range?).twice.and_return(true)
+      expect(memory_killer).to receive(:rss_within_range?)
+        .twice
+        .and_return(true)
 
       expect(memory_killer).not_to receive(:restart_sidekiq)
 
@@ -86,9 +94,12 @@ describe Gitlab::SidekiqDaemon::MemoryKiller do
     end
 
     it 'invoke restart_sidekiq when rss not in range' do
-      expect(memory_killer).to receive(:rss_within_range?).at_least(:once).and_return(false)
+      expect(memory_killer).to receive(:rss_within_range?)
+        .at_least(:once)
+        .and_return(false)
 
-      expect(memory_killer).to receive(:restart_sidekiq).at_least(:once)
+      expect(memory_killer).to receive(:restart_sidekiq)
+        .at_least(:once)
 
       subject
     end
@@ -97,10 +108,9 @@ describe Gitlab::SidekiqDaemon::MemoryKiller do
   describe '#stop_working' do
     subject { memory_killer.send(:stop_working)}
 
-    it 'changed enable? to false' do
-      expect(memory_killer.send(:enabled?)).to be true
-      subject
-      expect(memory_killer.send(:enabled?)).to be false
+    it 'changes enable? to false' do
+      expect { subject }.to change { memory_killer.send(:enabled?) }
+        .from(true).to(false)
     end
   end
 
@@ -121,8 +131,12 @@ describe Gitlab::SidekiqDaemon::MemoryKiller do
 
     it 'return true when everything is within limit' do
       expect(memory_killer).to receive(:get_rss).and_return(100)
-      expect(memory_killer).to receive(:soft_limit_rss).and_return(200)
-      expect(memory_killer).to receive(:hard_limit_rss).and_return(300)
+      expect(memory_killer).to receive(:get_soft_limit_rss).and_return(200)
+      expect(memory_killer).to receive(:get_hard_limit_rss).and_return(300)
+
+      expect(memory_killer).to receive(:refresh_state)
+        .with(:running)
+        .and_call_original
 
       expect(Gitlab::Metrics::System).to receive(:monotonic_time).and_call_original
       expect(memory_killer).not_to receive(:log_rss_out_of_range)
@@ -131,9 +145,17 @@ describe Gitlab::SidekiqDaemon::MemoryKiller do
     end
 
     it 'return false when rss exceeds hard_limit_rss' do
-      expect(memory_killer).to receive(:get_rss).and_return(400)
-      expect(memory_killer).to receive(:soft_limit_rss).at_least(:once).and_return(200)
-      expect(memory_killer).to receive(:hard_limit_rss).at_least(:once).and_return(300)
+      expect(memory_killer).to receive(:get_rss).at_least(:once).and_return(400)
+      expect(memory_killer).to receive(:get_soft_limit_rss).at_least(:once).and_return(200)
+      expect(memory_killer).to receive(:get_hard_limit_rss).at_least(:once).and_return(300)
+
+      expect(memory_killer).to receive(:refresh_state)
+        .with(:running)
+        .and_call_original
+
+      expect(memory_killer).to receive(:refresh_state)
+        .with(:above_soft_limit)
+        .and_call_original
 
       expect(Gitlab::Metrics::System).to receive(:monotonic_time).and_call_original
 
@@ -143,13 +165,21 @@ describe Gitlab::SidekiqDaemon::MemoryKiller do
     end
 
     it 'return false when rss exceed hard_limit_rss after a while' do
-      expect(memory_killer).to receive(:get_rss).and_return(250, 400)
-      expect(memory_killer).to receive(:soft_limit_rss).at_least(:once).and_return(200)
-      expect(memory_killer).to receive(:hard_limit_rss).at_least(:once).and_return(300)
+      expect(memory_killer).to receive(:get_rss).and_return(250, 400, 400)
+      expect(memory_killer).to receive(:get_soft_limit_rss).at_least(:once).and_return(200)
+      expect(memory_killer).to receive(:get_hard_limit_rss).at_least(:once).and_return(300)
+
+      expect(memory_killer).to receive(:refresh_state)
+        .with(:running)
+        .and_call_original
+
+      expect(memory_killer).to receive(:refresh_state)
+        .at_least(:once)
+        .with(:above_soft_limit)
+        .and_call_original
 
       expect(Gitlab::Metrics::System).to receive(:monotonic_time).twice.and_call_original
       expect(memory_killer).to receive(:sleep).with(check_interval_seconds)
-
       expect(memory_killer).to receive(:log_rss_out_of_range).with(400, 300, 200)
 
       expect(subject).to be false
@@ -157,8 +187,16 @@ describe Gitlab::SidekiqDaemon::MemoryKiller do
 
     it 'return true when rss below soft_limit_rss after a while within GRACE_BALLOON_SECONDS' do
       expect(memory_killer).to receive(:get_rss).and_return(250, 100)
-      expect(memory_killer).to receive(:soft_limit_rss).and_return(200, 200)
-      expect(memory_killer).to receive(:hard_limit_rss).and_return(300, 300)
+      expect(memory_killer).to receive(:get_soft_limit_rss).and_return(200, 200)
+      expect(memory_killer).to receive(:get_hard_limit_rss).and_return(300, 300)
+
+      expect(memory_killer).to receive(:refresh_state)
+        .with(:running)
+        .and_call_original
+
+      expect(memory_killer).to receive(:refresh_state)
+        .with(:above_soft_limit)
+        .and_call_original
 
       expect(Gitlab::Metrics::System).to receive(:monotonic_time).twice.and_call_original
       expect(memory_killer).to receive(:sleep).with(check_interval_seconds)
@@ -168,17 +206,27 @@ describe Gitlab::SidekiqDaemon::MemoryKiller do
       expect(subject).to be true
     end
 
-    it 'return false when rss exceed soft_limit_rss longer than GRACE_BALLOON_SECONDS' do
-      expect(memory_killer).to receive(:get_rss).exactly(4).times.and_return(250)
-      expect(memory_killer).to receive(:soft_limit_rss).exactly(5).times.and_return(200)
-      expect(memory_killer).to receive(:hard_limit_rss).exactly(5).times.and_return(300)
+    context 'when exceeding GRACE_BALLOON_SECONDS' do
+      let(:grace_balloon_seconds) { 0 }
 
-      expect(Gitlab::Metrics::System).to receive(:monotonic_time).exactly(5).times.and_call_original
-      expect(memory_killer).to receive(:sleep).exactly(3).times.with(check_interval_seconds).and_call_original
+      it 'return false when rss exceed soft_limit_rss' do
+        allow(memory_killer).to receive(:get_rss).and_return(250)
+        allow(memory_killer).to receive(:get_soft_limit_rss).and_return(200)
+        allow(memory_killer).to receive(:get_hard_limit_rss).and_return(300)
 
-      expect(memory_killer).to receive(:log_rss_out_of_range).with(250, 300, 200)
+        expect(memory_killer).to receive(:refresh_state)
+          .with(:running)
+          .and_call_original
 
-      expect(subject).to be false
+        expect(memory_killer).to receive(:refresh_state)
+          .with(:above_soft_limit)
+          .and_call_original
+
+        expect(memory_killer).to receive(:log_rss_out_of_range)
+          .with(250, 300, 200)
+
+        expect(subject).to be false
+      end
     end
   end
 
@@ -190,19 +238,42 @@ describe Gitlab::SidekiqDaemon::MemoryKiller do
     before do
       stub_const("#{described_class}::SHUTDOWN_TIMEOUT_SECONDS", shutdown_timeout_seconds)
       allow(Sidekiq).to receive(:options).and_return(timeout: 9)
+      allow(memory_killer).to receive(:get_rss).and_return(100)
+      allow(memory_killer).to receive(:get_soft_limit_rss).and_return(200)
+      allow(memory_killer).to receive(:get_hard_limit_rss).and_return(300)
     end
 
     it 'send signal' do
-      expect(memory_killer).to receive(:signal_and_wait).with(shutdown_timeout_seconds, 'SIGTSTP', 'stop fetching new jobs').ordered
-      expect(memory_killer).to receive(:signal_and_wait).with(11, 'SIGTERM', 'gracefully shut down').ordered
-      expect(memory_killer).to receive(:signal_pgroup).with('SIGKILL', 'die').ordered
+      expect(memory_killer).to receive(:refresh_state)
+        .with(:stop_fetching_new_jobs)
+        .ordered
+        .and_call_original
+      expect(memory_killer).to receive(:signal_and_wait)
+        .with(shutdown_timeout_seconds, 'SIGTSTP', 'stop fetching new jobs')
+        .ordered
+
+      expect(memory_killer).to receive(:refresh_state)
+        .with(:shutting_down)
+        .ordered
+        .and_call_original
+      expect(memory_killer).to receive(:signal_and_wait)
+        .with(11, 'SIGTERM', 'gracefully shut down')
+        .ordered
+
+      expect(memory_killer).to receive(:refresh_state)
+        .with(:killing_sidekiq)
+        .ordered
+        .and_call_original
+      expect(memory_killer).to receive(:signal_pgroup)
+        .with('SIGKILL', 'die')
+        .ordered
 
       subject
     end
   end
 
   describe '#signal_and_wait' do
-    let(:time) { 7 }
+    let(:time) { 0 }
     let(:signal) { 'my-signal' }
     let(:explanation) { 'my-explanation' }
     let(:check_interval_seconds) { 2 }
@@ -226,14 +297,17 @@ describe Gitlab::SidekiqDaemon::MemoryKiller do
     end
 
     it 'send signal and wait till deadline if any job not finished' do
-      expect(Process).to receive(:kill).with(signal, pid).ordered
-      expect(Gitlab::Metrics::System).to receive(:monotonic_time).and_call_original.at_least(:once)
+      expect(Process).to receive(:kill)
+        .with(signal, pid)
+        .ordered
+
+      expect(Gitlab::Metrics::System).to receive(:monotonic_time)
+        .and_call_original
+        .at_least(:once)
 
       expect(memory_killer).to receive(:enabled?).and_return(true).at_least(:once)
       expect(memory_killer).to receive(:any_jobs?).and_return(true).at_least(:once)
 
-      expect(memory_killer).to receive(:sleep).and_call_original.exactly(4).times
-
       subject
     end
   end
@@ -401,4 +475,27 @@ describe Gitlab::SidekiqDaemon::MemoryKiller do
       expect(subject).to eq(10)
     end
   end
+
+  describe '#refresh_state' do
+    let(:metrics) { memory_killer.instance_variable_get(:@metrics) }
+
+    subject { memory_killer.send(:refresh_state, :shutting_down) }
+
+    it 'calls gitlab metrics gauge set methods' do
+      expect(memory_killer).to receive(:get_rss) { 1010 }
+      expect(memory_killer).to receive(:get_soft_limit_rss) { 1020 }
+      expect(memory_killer).to receive(:get_hard_limit_rss) { 1040 }
+
+      expect(metrics[:sidekiq_memory_killer_phase]).to receive(:set)
+        .with({}, described_class::PHASE[:shutting_down])
+      expect(metrics[:sidekiq_current_rss]).to receive(:set)
+        .with({}, 1010)
+      expect(metrics[:sidekiq_memory_killer_soft_limit_rss]).to receive(:set)
+        .with({}, 1020)
+      expect(metrics[:sidekiq_memory_killer_hard_limit_rss]).to receive(:set)
+        .with({}, 1040)
+
+      subject
+    end
+  end
 end