refactor(core): let the profiler handle asymmetric events leniently

JoostK · thePunderWoman · commit 780e37241fc6 · 2025-11-17T17:40:10.000Z
Although the prior commit has made more profiler events guaranteed symmetric through the use of finally-blocks, there continue to be some situations that could potentially result in asymmetric events, e.g. application bootstrap doesn't guarantee symmetric events. This commit makes the profiler lenient to these situations by unrolling the stack past the asymmetric event data, eventually reaching the expected start event. (cherry picked from commit da9911f)
diff --git a/packages/core/src/render3/debug/chrome_dev_tools_performance.ts b/packages/core/src/render3/debug/chrome_dev_tools_performance.ts
@@ -71,14 +71,14 @@ function measureEnd(
   entryName: string,
   color: DevToolsColor,
 ) {
-  const top = eventsStack.pop();
-
-  assertDefined(top, 'Profiling error: could not find start event entry ' + startEvent);
-  assertEqual(
-    top[0],
-    startEvent,
-    `Profiling error: expected to see ${startEvent} event but got ${top[0]}`,
-  );
+  let top: stackEntry | undefined;
+
+  // The stack may be asymmetric when an end event for a prior start event is missing (e.g. when an exception
+  // has occurred), unroll the stack until a matching item has been found in that case.
+  do {
+    top = eventsStack.pop();
+    assertDefined(top, 'Profiling error: could not find start event entry ' + startEvent);
+  } while (top[0] !== startEvent);
 
   console.timeStamp(
     entryName,
diff --git a/packages/core/test/acceptance/chrome_dev_tools_performance_spec.ts b/packages/core/test/acceptance/chrome_dev_tools_performance_spec.ts
@@ -6,8 +6,10 @@
  * found in the LICENSE file at https://angular.dev/license
  */
 
-import {enableProfiling} from '../../src/render3/debug/chrome_dev_tools_performance';
 import {Component, HostAttributeToken, inject, Inject} from '../../src/core';
+import {enableProfiling} from '../../src/render3/debug/chrome_dev_tools_performance';
+import {profiler} from '../../src/render3/profiler';
+import {ProfilerEvent} from '../../src/render3/profiler_types';
 import {TestBed} from '../../testing';
 
 describe('Chrome DevTools Performance integration', () => {
@@ -59,5 +61,26 @@ describe('Chrome DevTools Performance integration', () => {
         stopProfiling();
       }
     });
+
+    it('should not crash when asymmetric events are processed', () => {
+      const timeStampSpy = spyOn(console, 'timeStamp');
+      const stopProfiling = enableProfiling();
+
+      try {
+        profiler(ProfilerEvent.ChangeDetectionSyncStart);
+        profiler(ProfilerEvent.ChangeDetectionStart);
+        profiler(ProfilerEvent.ChangeDetectionSyncEnd);
+
+        const calls = timeStampSpy.calls.all();
+        expect(calls.length).toBe(3);
+
+        const [syncStart, cdStart, syncEnd] = calls;
+        expect(syncStart.args[0]).toMatch(/^Event_/);
+        expect(cdStart.args[0]).toMatch(/^Event_/);
+        expect(syncEnd.args[0]).toMatch(/^Synchronization /);
+      } finally {
+        stopProfiling();
+      }
+    });
   });
 });
