perf_hooks: remove GC callbacks on zero observers count

When all existed PerformanceObserver instances removed for type `gc` GC
callbacks should be removed.

PR-URL: https://github.com/nodejs/node/pull/29444
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Minwoo Jung <minwoo@nodesource.com>

1 files changed, 12 insertions, 8 deletions

diff --git a/lib/perf_hooks.js b/lib/perf_hooks.js
index 453fc54eb9..1bf635790e 100644
--- a/lib/perf_hooks.js
+++ b/lib/perf_hooks.js
@@ -15,7 +15,8 @@ const {
   timeOriginTimestamp,
   timerify,
   constants,
-  setupGarbageCollectionTracking
+  installGarbageCollectionTracking,
+  removeGarbageCollectionTracking
 } = internalBinding('performance');
 
 const {
@@ -281,8 +282,6 @@ class PerformanceObserverEntryList {
   }
 }
 
-let gcTrackingIsEnabled = false;
-
 class PerformanceObserver extends AsyncResource {
   constructor(callback) {
     if (typeof callback !== 'function') {
@@ -319,6 +318,7 @@ class PerformanceObserver extends AsyncResource {
   }
 
   disconnect() {
+    const observerCountsGC = observerCounts[NODE_PERFORMANCE_ENTRY_TYPE_GC];
     const types = this[kTypes];
     const keys = Object.keys(types);
     for (var n = 0; n < keys.length; n++) {
@@ -329,6 +329,10 @@ class PerformanceObserver extends AsyncResource {
       }
     }
     this[kTypes] = {};
+    if (observerCountsGC === 1 &&
+      observerCounts[NODE_PERFORMANCE_ENTRY_TYPE_GC] === 0) {
+      removeGarbageCollectionTracking();
+    }
   }
 
   observe(options) {
@@ -342,12 +346,8 @@ class PerformanceObserver extends AsyncResource {
     if (entryTypes.length === 0) {
       throw new ERR_VALID_PERFORMANCE_ENTRY_TYPE();
     }
-    if (entryTypes.includes(NODE_PERFORMANCE_ENTRY_TYPE_GC) &&
-      !gcTrackingIsEnabled) {
-      setupGarbageCollectionTracking();
-      gcTrackingIsEnabled = true;
-    }
     this.disconnect();
+    const observerCountsGC = observerCounts[NODE_PERFORMANCE_ENTRY_TYPE_GC];
     this[kBuffer][kEntries] = [];
     L.init(this[kBuffer][kEntries]);
     this[kBuffering] = Boolean(options.buffered);
@@ -359,6 +359,10 @@ class PerformanceObserver extends AsyncResource {
       L.append(list, item);
       observerCounts[entryType]++;
     }
+    if (observerCountsGC === 0 &&
+      observerCounts[NODE_PERFORMANCE_ENTRY_TYPE_GC] === 1) {
+      installGarbageCollectionTracking();
+    }
   }
 }