babybird

A very fast standards-compliant ES2015 Promise library for node.

There are several fast promise implementations out there, like bluebird, but they all add a bunch of stuff that's not in the ES2015 Promise spec. Further, as they've added more and more features they've grown so complex that they can't be easily audited against the ES2015 spec (or the official test262 test suite).

The babybird library is a stripped-down "just ES2015" Promise implementation, which passes the Promises/A+ and test262 test suites. It is very competitive with the performance of bluebird, without having to give us standards compliance. On the doxbee benchmark running under node 5.1.0, babybird is 2.4 times faster than native Promises, 4 times faster than the Promise implementation in core-js, and almost 9 times faster than the Promise implementation in es6-shim. The performance improvement is even greater when running under node 0.10.

Further, babybird supports subclassing (as all ES2015 Promise implementations ought). This means that if you'd like additional bells and whistles on your Promises, you can add then via subclassing and without stomping on the global Promise. In fact, the prfun library provides much the same feature set as bluebird, but with a clean separation of concerns. Further, prfun runs on top of any ES2015-compliant Promise implementation, so if babybird is someday supplanted, you can just swap out the core Promise implementation underneath prfun without having to update any of your uses of the core ES2015 or extended prfun API.

Usage

npm install babybird

var Promise = require('babybird');

The babybird library plays very nicely with prfun, if you'd like a few bells and whistles with your library. I recommend creating a new module, named (say) promise.js, with the contents:

module.exports = require('prfun/wrap')(require('babybird'));

and then using the wrapped promises this way:

var Promise = require('./promise.js');

Benchmarks

These benchmarks are derived from the benchmarks included with bluebird. A few of the bluebird test cases have been forked to add "fair" versions, since bluebird obtained some of its speed by using a faster promisify method than that provided to other promise implementations, and by using a few bluebird-specific APIs which appeared to be tuned for the benchmark.

You can reproduce these results using npm run bench.

Node 0.10

results for 20000 parallel executions, 1 ms per I/O op

file                                         time(ms)  slowdown  memory(MB)
callbacks-baseline.js                             819      0.48  32.99
promises-bluebird.js                             1383      0.81  50.59
promises-bluebird-fair.js                        1715      1.00  39.02
promises-cscott-babybird-noall.js                1870      1.09  41.19
promises-cscott-babybird.js                      1925      1.12  61.81
promises-cscott-babybird-prfun.js                1991      1.16  48.60
promises-then-promise-es6.js                     3084      1.80  64.54
promises-then-promise.js                         3112      1.81  64.39
promises-paulmillr-es6shim.js                   12475      7.27  94.20
promises-zloirock-corejs.js                     18695     10.90  94.11

Platform info:
Linux 4.2.0-1-amd64 ia32
Node.JS 0.10.40
V8 3.14.5.9
Intel(R) Core(TM) i7 CPU       L 640  @ 2.13GHz × 4

Node 5.1.0

results for 20000 parallel executions, 1 ms per I/O op

file                                         time(ms)  slowdown  memory(MB)
callbacks-baseline.js                             826      0.53  29.29
promises-bluebird-generator.js                   1105      0.71  25.49
promises-bluebird-generator-fair.js              1113      0.72  28.27
promises-cscott-babybird-prfun-generator.js      1202      0.77  33.68
promises-bluebird-fair.js                        1553      1.00  51.38
promises-cscott-babybird-noall.js                1623      1.05  65.25
promises-bluebird.js                             1643      1.06  43.66
promises-cscott-babybird-prfun.js                1707      1.10  72.33
promises-cscott-babybird.js                      1724      1.11  72.82
promises-then-promise-es6.js                     2985      1.92  106.96
promises-then-promise.js                         3004      1.93  106.69
promises-ecmascript6-native.js                   3770      2.43  176.96
promises-zloirock-corejs.js                      6298      4.06  155.89
promises-paulmillr-es6shim.js                   13892      8.95  227.61

Platform info:
Linux 4.2.0-1-amd64 ia32
Node.JS 5.1.0
V8 4.6.85.31
Intel(R) Core(TM) i7 CPU       L 640  @ 2.13GHz × 4

License

Copyright (c) 2015 C. Scott Ananian

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.