test: deflake test-diagnostics-channel-memory-leak

Author: joyeecheung

test/parallel/parallel.status

@@ -5,9 +5,6 @@ prefix parallel
 # sample-test                        : PASS,FLAKY
 
 [true] # This section applies to all platforms
-# https://github.com/nodejs/node/pull/50327
-# Currently there's no reliable way to test it.
-test-diagnostics-channel-memory-leak: SKIP
 
 [$system==win32]
 # https://github.com/nodejs/node/issues/41206

test/parallel/test-diagnostics-channel-memory-leak.js

@@ -1,24 +1,40 @@
-// Flags: --expose-gc
+// Flags: --expose-internals --expose-internals --max-old-space-size=16
 'use strict';
 
 // This test ensures that diagnostic channel references aren't leaked.
 
 require('../common');
-const { ok } = require('assert');
-
-const { subscribe, unsubscribe } = require('diagnostics_channel');
+const assert = require('assert');
 
+const { subscribe, unsubscribe, Channel } = require('diagnostics_channel');
+const { internalBinding } = require('internal/test/binding');
+const { countObjectsWithPrototype } = internalBinding('heap_utils');
 function noop() {}
 
-const heapUsedBefore = process.memoryUsage().heapUsed;
-
-for (let i = 0; i < 1000; i++) {
-  subscribe(String(i), noop);
-  unsubscribe(String(i), noop);
+const initialCount = countObjectsWithPrototype(Channel.prototype);
+console.log('Initial count of diagnostics channels', initialCount);
+const outer = 1024;
+const inner = 16;
+let finished = 0;
+
+for (let i = 0; i < outer; i++) {
+  setImmediate(() => {
+    for (let j = 0; j < inner; j++) {
+      const key = String(i * inner + j);
+      subscribe(key, noop);
+      unsubscribe(key, noop);
+    }
+    if (++finished === outer) {
+      setImmediate(check);
+    }
+  });
 }
 
-global.gc();
-
-const heapUsedAfter = process.memoryUsage().heapUsed;
-
-ok(heapUsedBefore >= heapUsedAfter);
+function check() {
+  const afterCount = countObjectsWithPrototype(Channel.prototype);
+  console.log('Ending count of diagnostics channels', afterCount);
+  const remaining = afterCount - initialCount;
+  console.log('Remaining count of diagnostics channels', remaining);
+  console.log('Number of channels created', inner * outer);
+  assert(remaining < inner * outer);
+}