performance,events: use Map to store events in EventEmitter

benchmark/events/ee-add-remove.js

@@ -2,16 +2,23 @@
 const common = require('../common.js');
 const events = require('events');
 
-const bench = common.createBenchmark(main, { n: [1e6] });
+const bench = common.createBenchmark(main, {
+  n: [5e6],
+  staleEventsCount: [0, 5],
+  listenerCount: [1, 5],
+});
 
-function main({ n }) {
+function main({ n, staleEventsCount, listenerCount }) {
   const ee = new events.EventEmitter();
   const listeners = [];
 
   var k;
-  for (k = 0; k < 10; k += 1)
+  for (k = 0; k < listenerCount; k += 1)
     listeners.push(function() {});
 
+  for (k = 0; k < staleEventsCount; k++)
+    ee.on(`dummyunused${k}`, () => {});
+
   bench.start();
   for (var i = 0; i < n; i += 1) {
     const dummy = (i % 2 === 0) ? 'dummy0' : 'dummy1';

benchmark/events/ee-emit-multi.js

@@ -0,0 +1,28 @@
+'use strict';
+const common = require('../common.js');
+const EventEmitter = require('events').EventEmitter;
+
+const bench = common.createBenchmark(main, {
+  n: [2e7],
+  listenerCount: [1, 5, 10],
+});
+
+function main({ n, listenerCount }) {
+  const ee = new EventEmitter();
+
+  for (var k = 0; k < listenerCount; k += 1) {
+    ee.on('dummy', function() {});
+    ee.on(`dummy${k}`, function() {});
+  }
+
+  bench.start();
+  for (var i = 0; i < n; i += 1) {
+    if (i % 3 === 0)
+      ee.emit('dummy', true, 5);
+    else if (i % 2 === 0)
+      ee.emit('dummy', true, 5, 10, false);
+    else
+      ee.emit('dummy');
+  }
+  bench.end(n);
+}

benchmark/events/ee-emit.js

@@ -5,13 +5,13 @@ const EventEmitter = require('events').EventEmitter;
 const bench = common.createBenchmark(main, {
   n: [2e6],
   argc: [0, 2, 4, 10],
-  listeners: [1, 5, 10],
+  listenerCount: [1, 5, 10],
 });
 
-function main({ n, argc, listeners }) {
+function main({ n, argc, listenerCount }) {
   const ee = new EventEmitter();
 
-  for (var k = 0; k < listeners; k += 1)
+  for (var k = 0; k < listenerCount; k += 1)
     ee.on('dummy', function() {});
 
   var i;

benchmark/events/ee-event-names.js

@@ -0,0 +1,28 @@
+'use strict';
+const common = require('../common.js');
+const EventEmitter = require('events').EventEmitter;
+
+const bench = common.createBenchmark(main, { n: [1e6] });
+
+function main({ n }) {
+  const ee = new EventEmitter();
+
+  for (var k = 0; k < 9; k += 1) {
+    ee.on(`dummy0${k}`, function() {});
+    ee.on(`dummy1${k}`, function() {});
+    ee.on(`dummy2${k}`, function() {});
+  }
+
+  ee.removeAllListeners('dummy01');
+  ee.removeAllListeners('dummy11');
+  ee.removeAllListeners('dummy21');
+  ee.removeAllListeners('dummy06');
+  ee.removeAllListeners('dummy16');
+  ee.removeAllListeners('dummy26');
+
+  bench.start();
+  for (var i = 0; i < n; i += 1) {
+    ee.eventNames();
+  }
+  bench.end(n);
+}

benchmark/events/ee-listeners-many.js

@@ -2,7 +2,7 @@
 const common = require('../common.js');
 const EventEmitter = require('events').EventEmitter;
 
-const bench = common.createBenchmark(main, { n: [5e6] });
+const bench = common.createBenchmark(main, { n: [1e7] });
 
 function main({ n }) {
   const ee = new EventEmitter();

benchmark/events/ee-once.js

@@ -2,17 +2,22 @@
 const common = require('../common.js');
 const EventEmitter = require('events').EventEmitter;
 
-const bench = common.createBenchmark(main, { n: [2e7] });
+const bench = common.createBenchmark(main, {
+  n: [5e6],
+  listenerCount: [1, 5, 10],
+});
 
-function main({ n }) {
+
+function main({ n, listenerCount }) {
   const ee = new EventEmitter();
 
   function listener() {}
 
   bench.start();
-  for (var i = 0; i < n; i += 1) {
+  for (var i = 0; i < n; ++i) {
     const dummy = (i % 2 === 0) ? 'dummy0' : 'dummy1';
-    ee.once(dummy, listener);
+    for (var j = 0; j < listenerCount; ++j)
+      ee.once(dummy, listener);
     ee.emit(dummy);
   }
   bench.end(n);

deps/v8/src/builtins/builtins-collections-gen.cc

@@ -1474,14 +1474,17 @@ TF_BUILTIN(MapPrototypeDelete, CollectionsBuiltinsAssembler) {
       LoadFixedArrayElement(table, OrderedHashMap::kNumberOfBucketsIndex);
 
   // If there fewer elements than #buckets / 2, shrink the table.
-  Label shrink(this);
-  GotoIf(SmiLessThan(SmiAdd(number_of_elements, number_of_elements),
-                     number_of_buckets),
-         &shrink);
-  Return(TrueConstant());
+  Label dont_shrink(this);
+  GotoIf(SmiGreaterThanOrEqual(SmiAdd(number_of_elements, number_of_elements),
+                               number_of_buckets),
+         &dont_shrink);
+  // If #buckets is less than 8 then don't shrink the table
+  GotoIf(SmiLessThan(number_of_buckets, SmiConstant(8)),
+         &dont_shrink);
 
-  BIND(&shrink);
   CallRuntime(Runtime::kMapShrink, context, receiver);
+
+  BIND(&dont_shrink);
   Return(TrueConstant());
 }