Add removeListenerWhileNotifying benchmark for ChangeNotifier (#78161)
diff --git a/dev/benchmarks/microbenchmarks/lib/foundation/change_notifier_bench.dart b/dev/benchmarks/microbenchmarks/lib/foundation/change_notifier_bench.dart
index 64dfdaa..0ab7a40 100644
--- a/dev/benchmarks/microbenchmarks/lib/foundation/change_notifier_bench.dart
+++ b/dev/benchmarks/microbenchmarks/lib/foundation/change_notifier_bench.dart
@@ -6,108 +6,178 @@
import '../common.dart';
-const int _kNumIterations = 1000;
-const double _scale = 1000.0 / _kNumIterations;
+const int _kNumIterations = 65536;
const int _kNumWarmUp = 100;
+const int _kScale = 1000;
void main() {
assert(false, "Don't run benchmarks in checked mode! Use 'flutter run --release'.");
- void listener() {}
- void listener2() {}
- void listener3() {}
- void listener4() {}
- void listener5() {}
+ // In the following benchmarks, we won't remove the listeners when we don't
+ // want to measure removeListener because we know that everything will be
+ // GC'ed in the end.
+ // Not removing listeners would cause memory leaks in a real application.
- // Warm up lap
- for (int i = 0; i < _kNumWarmUp; i += 1) {
- _Notifier()
- ..addListener(listener)
- ..addListener(listener2)
- ..addListener(listener3)
- ..addListener(listener4)
- ..addListener(listener5)
- ..notify()
- ..removeListener(listener)
- ..removeListener(listener2)
- ..removeListener(listener3)
- ..removeListener(listener4)
- ..removeListener(listener5);
- }
-
- final Stopwatch addListenerWatch = Stopwatch();
- final Stopwatch removeListenerWatch = Stopwatch();
- final Stopwatch notifyListenersWatch = Stopwatch();
final BenchmarkResultPrinter printer = BenchmarkResultPrinter();
- for (int listenersCount = 0; listenersCount <= 5; listenersCount++) {
+ void runAddListenerBenchmark(int iteration, {bool addResult = true}) {
+ const String name = 'add';
+ for (int listenerCount = 1; listenerCount <= 5; listenerCount += 1) {
+ final List<_Notifier> notifiers = List<_Notifier>.generate(
+ iteration,
+ (_) => _Notifier(),
+ growable: false,
+ );
- for (int j = 0; j < _kNumIterations; j += 1) {
- final _Notifier notifier = _Notifier();
- addListenerWatch.start();
-
- notifier.addListener(listener);
- if (listenersCount > 1)
- notifier.addListener(listener2);
- if (listenersCount > 2)
- notifier.addListener(listener3);
- if (listenersCount > 3)
- notifier.addListener(listener4);
- if (listenersCount > 4)
- notifier.addListener(listener5);
-
- addListenerWatch.stop();
- notifyListenersWatch.start();
-
- notifier.notify();
-
- notifyListenersWatch.stop();
- removeListenerWatch.start();
-
- // Remove listeners in reverse order to evaluate the worse-case scenario:
- // the listener removed is the last listener
- if (listenersCount > 4)
- notifier.removeListener(listener5);
- if (listenersCount > 3)
- notifier.removeListener(listener4);
- if (listenersCount > 2)
- notifier.removeListener(listener3);
- if (listenersCount > 1)
- notifier.removeListener(listener2);
- notifier.removeListener(listener);
-
- removeListenerWatch.stop();
+ final Stopwatch watch = Stopwatch();
+ watch.start();
+ for (int i = 0; i < iteration; i += 1) {
+ for (int l = 0; l < listenerCount; l += 1) {
+ notifiers[i].addListener(() {});
+ }
+ }
+ watch.stop();
+ final int elapsed = watch.elapsedMicroseconds;
+ final double averagePerIteration = elapsed / iteration;
+ if (addResult)
+ printer.addResult(
+ description: '$name ($listenerCount listeners)',
+ value: averagePerIteration * _kScale,
+ unit: 'ns per iteration',
+ name: '$name$listenerCount',
+ );
}
-
- final int notifyListener = notifyListenersWatch.elapsedMicroseconds;
- notifyListenersWatch.reset();
- final int addListenerElapsed = addListenerWatch.elapsedMicroseconds;
- addListenerWatch.reset();
- final int removeListenerElapsed = removeListenerWatch.elapsedMicroseconds;
- removeListenerWatch.reset();
-
- printer.addResult(
- description: 'addListener ($listenersCount listeners)',
- value: addListenerElapsed * _scale,
- unit: 'ns per iteration',
- name: 'addListener${listenersCount}_iteration',
- );
-
- printer.addResult(
- description: 'removeListener ($listenersCount listeners)',
- value: removeListenerElapsed * _scale,
- unit: 'ns per iteration',
- name: 'removeListener${listenersCount}_iteration',
- );
-
- printer.addResult(
- description: 'notifyListener ($listenersCount listeners)',
- value: notifyListener * _scale,
- unit: 'ns per iteration',
- name: 'notifyListener${listenersCount}_iteration',
- );
}
+ void runNotifyListenerBenchmark(int iteration, {bool addResult = true}) {
+ const String name = 'notify';
+
+ for (int listenerCount = 0; listenerCount <= 5; listenerCount += 1) {
+ final _Notifier notifier = _Notifier();
+ for (int i = 1; i <= listenerCount; i += 1) {
+ notifier.addListener(() {});
+ }
+ final Stopwatch watch = Stopwatch();
+ watch.start();
+ for (int i = 0; i < iteration; i += 1) {
+ notifier.notify();
+ }
+ watch.stop();
+ final int elapsed = watch.elapsedMicroseconds;
+ final double averagePerIteration = elapsed / iteration;
+ if (addResult)
+ printer.addResult(
+ description: '$name ($listenerCount listeners)',
+ value: averagePerIteration * _kScale,
+ unit: 'ns per iteration',
+ name: '$name$listenerCount',
+ );
+ }
+ }
+
+ void runRemoveListenerBenchmark(int iteration, {bool addResult = true}) {
+ const String name = 'remove';
+ final List<VoidCallback> listeners = <VoidCallback>[
+ () {},
+ () {},
+ () {},
+ () {},
+ () {},
+ ];
+ for (int listenerCount = 1; listenerCount <= 5; listenerCount += 1) {
+ final List<_Notifier> notifiers = List<_Notifier>.generate(
+ iteration,
+ (_) {
+ final _Notifier notifier = _Notifier();
+ for (int l = 0; l < listenerCount; l += 1) {
+ notifier.addListener(listeners[l]);
+ }
+ return notifier;
+ },
+ growable: false,
+ );
+
+ final Stopwatch watch = Stopwatch();
+ watch.start();
+ for (int i = 0; i < iteration; i += 1) {
+ for (int l = 0; l < listenerCount; l += 1) {
+ notifiers[i].removeListener(listeners[l]);
+ }
+ }
+ watch.stop();
+ final int elapsed = watch.elapsedMicroseconds;
+ final double averagePerIteration = elapsed / iteration;
+ if (addResult)
+ printer.addResult(
+ description: '$name ($listenerCount listeners)',
+ value: averagePerIteration * _kScale,
+ unit: 'ns per iteration',
+ name: '$name$listenerCount',
+ );
+ }
+ }
+
+ void runRemoveListenerWhileNotifyingBenchmark(int iteration,
+ {bool addResult = true}) {
+ const String name = 'removeWhileNotify';
+
+ final List<VoidCallback> listeners = <VoidCallback>[
+ () {},
+ () {},
+ () {},
+ () {},
+ () {},
+ ];
+ for (int listenerCount = 1; listenerCount <= 5; listenerCount += 1) {
+ final List<_Notifier> notifiers = List<_Notifier>.generate(
+ iteration,
+ (_) {
+ final _Notifier notifier = _Notifier();
+ notifier.addListener(() {
+ // This listener will remove all other listeners. So that only this
+ // one is called and measured.
+ for (int l = 0; l < listenerCount; l += 1) {
+ notifier.removeListener(listeners[l]);
+ }
+ });
+ for (int l = 0; l < listenerCount; l += 1) {
+ notifier.addListener(listeners[l]);
+ }
+ return notifier;
+ },
+ growable: false,
+ );
+
+ final Stopwatch watch = Stopwatch();
+ watch.start();
+ for (int i = 0; i < iteration; i += 1) {
+ notifiers[i].notify();
+ }
+ watch.stop();
+ final int elapsed = watch.elapsedMicroseconds;
+ final double averagePerIteration = elapsed / iteration;
+ if (addResult)
+ printer.addResult(
+ description: '$name ($listenerCount listeners)',
+ value: averagePerIteration * _kScale,
+ unit: 'ns per iteration',
+ name: '$name$listenerCount',
+ );
+ }
+ }
+
+ runAddListenerBenchmark(_kNumWarmUp, addResult: false);
+ runAddListenerBenchmark(_kNumIterations, addResult: true);
+
+ runNotifyListenerBenchmark(_kNumWarmUp, addResult: false);
+ runNotifyListenerBenchmark(_kNumIterations, addResult: true);
+
+ runRemoveListenerBenchmark(_kNumWarmUp, addResult: false);
+ runRemoveListenerBenchmark(_kNumIterations, addResult: true);
+
+ runRemoveListenerWhileNotifyingBenchmark(_kNumWarmUp, addResult: false);
+ runRemoveListenerWhileNotifyingBenchmark(_kNumIterations, addResult: true);
+
printer.printToStdout();
}
