From 016b7ba6168a4a59024af92f10109325231c96c6 Mon Sep 17 00:00:00 2001
From: James M Snell <jasnell@gmail.com>
Date: Tue, 27 Jul 2021 10:06:13 -0700
Subject: [PATCH] perf_hooks: fix PerformanceObserver gc crash

Signed-off-by: James M Snell <jasnell@gmail.com>
Fixes: https://github.com/nodejs/node/issues/39548

PR-URL: https://github.com/nodejs/node/pull/39550
Reviewed-By: Bryan English <bryan@bryanenglish.com>
Reviewed-By: Chengzhong Wu <legendecas@gmail.com>
---
 lib/internal/perf/observe.js        |  1 +
 test/parallel/test-perf-gc-crash.js | 25 +++++++++++++++++++++++++
 2 files changed, 26 insertions(+)
 create mode 100644 test/parallel/test-perf-gc-crash.js

diff --git a/lib/internal/perf/observe.js b/lib/internal/perf/observe.js
index 67a37175a179b3..eadc617452e952 100644
--- a/lib/internal/perf/observe.js
+++ b/lib/internal/perf/observe.js
@@ -132,6 +132,7 @@ function maybeDecrementObserverCounts(entryTypes) {
       if (observerType === NODE_PERFORMANCE_ENTRY_TYPE_GC &&
           observerCounts[observerType] === 0) {
         removeGarbageCollectionTracking();
+        gcTrackingInstalled = false;
       }
     }
   }
diff --git a/test/parallel/test-perf-gc-crash.js b/test/parallel/test-perf-gc-crash.js
new file mode 100644
index 00000000000000..d980e91a2f2799
--- /dev/null
+++ b/test/parallel/test-perf-gc-crash.js
@@ -0,0 +1,25 @@
+'use strict';
+
+require('../common');
+
+// Refers to https://github.com/nodejs/node/issues/39548
+
+// The test fails if this crashes. If it closes normally,
+// then all is good.
+
+const {
+  PerformanceObserver,
+} = require('perf_hooks');
+
+// We don't actually care if the observer callback is called here.
+const gcObserver = new PerformanceObserver(() => {});
+
+gcObserver.observe({ entryTypes: ['gc'] });
+
+gcObserver.disconnect();
+
+const gcObserver2 = new PerformanceObserver(() => {});
+
+gcObserver2.observe({ entryTypes: ['gc'] });
+
+gcObserver2.disconnect();