perf_hooks: fix PerformanceObserver 'gc' crash

Signed-off-by: James M Snell <jasnell@gmail.com>
Fixes: #38412
PR-URL: #38414
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Zijian Liu <lxxyxzj@gmail.com>

Author: jasnell

lib/internal/perf/observe.js

@@ -72,6 +72,8 @@ const kDeprecationMessage =
 constkTypeSingle=0;
 constkTypeMultiple=1;
 
+letgcTrackingInstalled=false;
+
 constkSupportedEntryTypes=ObjectFreeze([
 'function',
 'gc',
@@ -124,8 +126,11 @@ function maybeIncrementObserverCount(type) {
 
 if(observerType!==undefined){
 observerCounts[observerType]++;
-if(observerType===NODE_PERFORMANCE_ENTRY_TYPE_GC)
+if(!gcTrackingInstalled&&
+observerType===NODE_PERFORMANCE_ENTRY_TYPE_GC){
 installGarbageCollectionTracking();
+gcTrackingInstalled=true;
+}
 }
 }
 

test/parallel/test-performanceobserver-gc.js

@@ -0,0 +1,17 @@
+'use strict';
+
+require('../common');
+
+// Verifies that setting up two observers to listen
+// to gc performance does not crash.
+
+const{
+ PerformanceObserver,
+}=require('perf_hooks');
+
+// We don't actually care if the callback is ever invoked in this test
+constobs=newPerformanceObserver(()=>{});
+constobs2=newPerformanceObserver(()=>{});
+
+obs.observe({type: 'gc'});
+obs2.observe({type: 'gc'});