Sample sharedmem stats every second too

Summary: We're sampling CGroup memory stats every second. We might as well sample the same info from shared memory. This will let us see which steps are growing our shared memory heap the most.

Reviewed By: mroch

Differential Revision: D16360265

fbshipit-source-id: 75bfbe3e3f343fa43d28c03fc8bcaa3ab777d970

Author: gabelevi

src/services/inference/types_js.ml

@@ -50,12 +50,17 @@ let filter_duplicate_provider map file =
 
 let with_memory_info callback =
   let%lwt cgroup_stats = CGroup.get_stats () in
-  callback ~cgroup_stats;
+  (* Reading hash_stats while workers are writing can cause assertion errors *)
+  let hash_stats = try Some (SharedMem_js.hash_stats ()) with _ -> None in
+  let heap_size = SharedMem_js.heap_size () in
+  callback ~cgroup_stats ~hash_stats ~heap_size;
   Lwt.return_unit
 
 module MemorySamplingLoop = LwtLoop.Make (struct
   type acc =
     cgroup_stats:(CGroup.stats, string) result ->
+    hash_stats:SharedMem_js.table_stats option->
+    heap_size:int ->
     unit
   let main callback =
     let%lwt () = with_memory_info callback in
@@ -87,7 +92,29 @@ let with_timer_lwt =
     )
   in
 
-  let sample_memory timer profiling ~cgroup_stats =
+  let sample_memory timer profiling ~cgroup_stats ~hash_stats ~heap_size =
+    Profiling_js.sample_memory profiling
+      ~group:timer
+      ~metric:"heap"
+      ~value:(float heap_size);
+
+    Option.iter hash_stats ~f:(fun {SharedMem_js.nonempty_slots; used_slots; slots;} ->
+      Profiling_js.sample_memory profiling
+        ~group:timer
+        ~metric:"hash_nonempty_slots"
+        ~value:(float nonempty_slots);
+
+      Profiling_js.sample_memory profiling
+        ~group:timer
+        ~metric:"hash_used_slots"
+        ~value:(float used_slots);
+
+      Profiling_js.sample_memory profiling
+        ~group:timer
+        ~metric:"hash_slots"
+        ~value:(float slots)
+    );
+
     match cgroup_stats with
     | Error _ -> ()
     | Ok { CGroup.total; total_swap; anon; file; shmem; } -> begin