1 files changed, 47 insertions, 0 deletions
diff --git a/lib/gitlab/memory/watchdog/monitor/unique_memory_growth.rb b/lib/gitlab/memory/watchdog/monitor/unique_memory_growth.rb
new file mode 100644
index 00000000000..2a1512c4cff
--- /dev/null
+++ b/lib/gitlab/memory/watchdog/monitor/unique_memory_growth.rb
@@ -0,0 +1,47 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Memory
+    class Watchdog
+      module Monitor
+        class UniqueMemoryGrowth
+          attr_reader :max_mem_growth
+
+          def initialize(max_mem_growth:)
+            @max_mem_growth = max_mem_growth
+          end
+
+          def call
+            worker_uss = Gitlab::Metrics::System.memory_usage_uss_pss[:uss]
+            reference_uss = reference_mem[:uss]
+            memory_limit = max_mem_growth * reference_uss
+
+            return { threshold_violated: false, payload: {} } unless worker_uss > memory_limit
+
+            { threshold_violated: true, payload: payload(worker_uss, reference_uss, memory_limit) }
+          end
+
+          private
+
+          def payload(worker_uss, reference_uss, memory_limit)
+            {
+              message: 'memory limit exceeded',
+              memwd_uss_bytes: worker_uss,
+              memwd_ref_uss_bytes: reference_uss,
+              memwd_max_uss_bytes: memory_limit
+            }
+          end
+
+          # On pre-fork systems this would be the primary process memory from which workers fork.
+          # Otherwise it is the current process' memory.
+          #
+          # We initialize this lazily because in the initializer the application may not have
+          # finished booting yet, which would yield an incorrect baseline.
+          def reference_mem
+            @reference_mem ||= Gitlab::Metrics::System.memory_usage_uss_pss(pid: Gitlab::Cluster::PRIMARY_PID)
+          end
+        end
+      end
+    end
+  end
+end