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timers: improve setImmediate() performance
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This commit improves setImmediate() performance by moving the
try-finally block that wraps callback execution into a separate
function because currently v8 never tries to optimize functions
that contain try-finally blocks.

With this change, there is a ~20-40% improvement in the included
setImmediate() depth benchmarks. The breadth benchmarks show a slight
improvement.

PR-URL: #4169
Reviewed-By: Minwoo Jung <[email protected]>
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Ben Noordhuis <[email protected]>
Reviewed-By: Jeremiah Senkpiel <[email protected]>
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mscdex authored and Fishrock123 committed Mar 22, 2016
1 parent b1a4870 commit d3654d8
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Showing 5 changed files with 141 additions and 19 deletions.
28 changes: 28 additions & 0 deletions benchmark/misc/set-immediate-breadth-args.js
Original file line number Diff line number Diff line change
@@ -0,0 +1,28 @@
'use strict';

const common = require('../common.js');
const bench = common.createBenchmark(main, {
millions: [5]
});

function main(conf) {
const N = +conf.millions * 1e6;

process.on('exit', function() {
bench.end(N / 1e6);
});

function cb1(arg1) {}
function cb2(arg1, arg2) {}
function cb3(arg1, arg2, arg3) {}

bench.start();
for (let i = 0; i < N; i++) {
if (i % 3 === 0)
setImmediate(cb3, 512, true, null);
else if (i % 2 === 0)
setImmediate(cb2, false, 5.1);
else
setImmediate(cb1, 0);
}
}
21 changes: 21 additions & 0 deletions benchmark/misc/set-immediate-breadth.js
Original file line number Diff line number Diff line change
@@ -0,0 +1,21 @@
'use strict';

const common = require('../common.js');
const bench = common.createBenchmark(main, {
millions: [10]
});

function main(conf) {
const N = +conf.millions * 1e6;

process.on('exit', function() {
bench.end(N / 1e6);
});

function cb() {}

bench.start();
for (let i = 0; i < N; i++) {
setImmediate(cb);
}
}
47 changes: 47 additions & 0 deletions benchmark/misc/set-immediate-depth-args.js
Original file line number Diff line number Diff line change
@@ -0,0 +1,47 @@
'use strict';

const common = require('../common.js');
const bench = common.createBenchmark(main, {
millions: [10]
});

function main(conf) {
const N = +conf.millions * 1e6;

process.on('exit', function() {
bench.end(N / 1e6);
});

function cb3(n, arg2, arg3) {
if (--n) {
if (n % 3 === 0)
setImmediate(cb3, n, true, null);
else if (n % 2 === 0)
setImmediate(cb2, n, 5.1);
else
setImmediate(cb1, n);
}
}
function cb2(n, arg2) {
if (--n) {
if (n % 3 === 0)
setImmediate(cb3, n, true, null);
else if (n % 2 === 0)
setImmediate(cb2, n, 5.1);
else
setImmediate(cb1, n);
}
}
function cb1(n) {
if (--n) {
if (n % 3 === 0)
setImmediate(cb3, n, true, null);
else if (n % 2 === 0)
setImmediate(cb2, n, 5.1);
else
setImmediate(cb1, n);
}
}
bench.start();
setImmediate(cb1, N);
}
22 changes: 22 additions & 0 deletions benchmark/misc/set-immediate-depth.js
Original file line number Diff line number Diff line change
@@ -0,0 +1,22 @@
'use strict';

const common = require('../common.js');
const bench = common.createBenchmark(main, {
millions: [10]
});

function main(conf) {
const N = +conf.millions * 1e6;
let n = N;

process.on('exit', function() {
bench.end(N / 1e6);
});

bench.start();
setImmediate(onNextTick);
function onNextTick() {
if (--n)
setImmediate(onNextTick);
}
}
42 changes: 23 additions & 19 deletions lib/timers.js
Original file line number Diff line number Diff line change
Expand Up @@ -215,8 +215,8 @@ function listOnTimeout() {
}


// An optimization so that the try/finally only de-optimizes what is in this
// smaller function.
// An optimization so that the try/finally only de-optimizes (since at least v8
// 4.7) what is in this smaller function.
function tryOnTimeout(timer, list) {
timer._called = true;
var threw = true;
Expand Down Expand Up @@ -511,23 +511,7 @@ function processImmediate() {
if (domain)
domain.enter();

var threw = true;
try {
immediate._onImmediate();
threw = false;
} finally {
if (threw) {
if (!L.isEmpty(queue)) {
// Handle any remaining on next tick, assuming we're still
// alive to do so.
while (!L.isEmpty(immediateQueue)) {
L.append(queue, L.shift(immediateQueue));
}
immediateQueue = queue;
process.nextTick(processImmediate);
}
}
}
tryOnImmediate(immediate, queue);

if (domain)
domain.exit();
Expand All @@ -542,6 +526,26 @@ function processImmediate() {
}


// An optimization so that the try/finally only de-optimizes (since at least v8
// 4.7) what is in this smaller function.
function tryOnImmediate(immediate, queue) {
var threw = true;
try {
immediate._onImmediate();
threw = false;
} finally {
if (threw && !L.isEmpty(queue)) {
// Handle any remaining on next tick, assuming we're still alive to do so.
while (!L.isEmpty(immediateQueue)) {
L.append(queue, L.shift(immediateQueue));
}
immediateQueue = queue;
process.nextTick(processImmediate);
}
}
}


function Immediate() { }

Immediate.prototype.domain = undefined;
Expand Down

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