msgpackr

The msgpackr package is an extremely fast MessagePack NodeJS/JavaScript implementation. Currently, it is significantly faster than any other known implementations, faster than Avro (for JS), and generally faster than native V8 JSON.stringify/parse. It also includes an optional record extension (the r in msgpackr), for defining record structures that makes MessagePack even faster and more compact, often over twice as fast as even native JSON functions and several times faster than other JS implementations. See the performance section for more details.

Basic Usage

Install with:

npm i msgpackr

And import or require it for basic standard serialization/encoding (pack) and deserialization/decoding (unpack) functions:

import { unpack, pack } from 'msgpackr';
let serializedAsBuffer = pack(value);
let data = unpack(serializedAsBuffer);

This pack function will generate standard MessagePack without any extensions that should be compatible with any standard MessagePack parser/decoder. It will serialize JavaScript objects as MessagePack maps by default. The unpack function will deserialize MessagePack maps as an Object with the properties from the map.

Node Usage

The msgpackr package runs on any modern JS platform, but is optimized for NodeJS usage (and will use a node addon for performance boost as an optional dependency).

Streams

We can use the including streaming functionality (which further improves performance). The PackrStream is a NodeJS transform stream that can be used to serialize objects to a binary stream (writing to network/socket, IPC, etc.), and the UnpackrStream can be used to deserialize objects from a binary sream (reading from network/socket, etc.):

import { PackrStream } from 'msgpackr';
let stream = PackrStream();
stream.write(myData);

Or for a full example of sending and receiving data on a stream:

import { PackrStream } from 'msgpackr';
let sendingStream = PackrStream();
let receivingStream = UnpackrStream();
// we are just piping to our own stream, but normally you would send and
// receive over some type of inter-process or network connection.
sendingStream.pipe(receivingStream);
sendingStream.write(myData);
receivingStream.on('data', (data) => {
	// received data
});

The PackrStream and UnpackrStream instances will have also the record structure extension enabled by default (see below).

Alternate Terminology

If you prefer to use encoder/decode terminology, msgpackr exports aliases, so decode is equivalent to unpack, encode is pack, Encoder is Packr, Decoder is Unpackr, and EncoderStream and DecoderStream can be used as well.

Browser Usage

Msgpackr works as standalone JavaScript as well, and runs on modern browsers. It includes a bundled script for ease of direct loading. For module-based development, it is recommended that you directly import the module of interest, to minimize dependencies that get pulled into your application:

import { unpack } from 'msgpackr/unpack' // if you only need to unpack

(It is worth noting that while msgpackr works well in modern browsers, the MessagePack format itself is usually not an ideal format for web use. If you want compact data, brotli or gzip are most effective in compressing, and MessagePack's character frequency tends to defeat Huffman encoding used by these standard compression algorithms, resulting in less compact data than compressed JSON. The modern browser architecture is heavily optimized for parsing JSON from HTTP traffic, and it is difficult to achieve the same level of overall efficiency and ease with MessagePack.)

Record / Object Structures

There is a critical difference between maps (or dictionaries) that hold an arbitrary set of keys and values (JavaScript Map is designed for these), and records or object structures that have a well-defined set of fields. Typical JS objects/records may have many instances re(use) the same structure. By using the record extension, this distinction is preserved in MessagePack and the encoding can reuse structures and not only provides better type preservation, but yield much more compact encodings and increase decoding performance by 2-3x. Msgpackr automatically generates record definitions that are reused and referenced by objects with the same structure. There are a number of ways to use this to our advantage. For large object structures with repeating nested objects with similar structures, simply serializing with the record extension can yield significant benefits. To use the record structures extension, we create a new Packr instance. By default a new Packr instance will have the record extension enabled:

import { Packr } from 'msgpackr';
let packr = Packr();
packr.pack(bigDataWithLotsOfObjects);

Another way to further leverage the benefits of the msgpackr record structures is to use streams that naturally allow for data to reuse based on previous record structures. The stream classes have the record structure extension enabled by default and provide excellent out-of-the-box performance.

When creating a new Packr, Unpackr, PackrStream, or UnpackrStream instance, we can enable or disable the record structure extension with the useRecords property. When this is false, the record structure extension will be disabled (standard/compatibility mode), and all objects will revert to being serialized using MessageMap maps, and all maps will be deserialized to JS Objects as properties (like the standalone pack and unpack functions).

Shared Record Structures

Another useful way of using msgpackr, and the record extension, is for storing data in a databases, files, or other storage systems. If a number of objects with common data structures are being stored, a shared structure can be used to greatly improve data storage and deserialization efficiency. We just need to provide a way to store the generated shared structure so it is available to deserialize stored data in the future:

import { Packr } from 'msgpackr';
let packr = Packr({
	getStructures() {
		// storing our data in file (but we could also store in a db or key-value store)
		return unpack(readFileSync('my-shared-structures.mp')) || [];
	},
	saveStructures(structures) {
		writeFileSync('my-shared-structures.mp', pack(structures))
	},
	structures: []
});

Msgpackr will automatically add and saves structures as it encounters any new object structures (up to a limit of 32). It will always add structures in an incremental/compatible way: Any object encoded with an earlier structure can be decoded with a later version (as long as it is persisted).

Options

The following options properties can be provided to the Packr or Unpackr constructor:

• useRecords - Setting this to false disables the record extension and stores JavaScript objects as MessagePack maps, and unpacks maps as JavaScript Objects, which ensures compatibilty with other decoders.
• structures - Provides the array of structures that is to be used for record extension, if you want the structures saved and used again.
• mapsAsObjects - If true, this will decode MessagePack maps and JS Objects with the map entries decoded to object properties. If false, maps are decoded as JavaScript Maps. This is disabled by default if useRecords is enabled (which allows Maps to be preserved), and is enabled by default if useRecords is disabled.
• variableMapSize - This will use varying map size definition (fixmap, map16, map32) based on the number of keys when encoding objects, which yields slightly more compact encodings (for small objects), but is typically 5-10% slower during encoding. This is only relevant when record extension is disabled.
• useTimestamp32 - Encode JS Dates in 32-bit format when possible. This causes the milliseconds to be dropped, but is a much more efficient encoding of dates.

Performance

Msgpackr is fast. Really fast. Here is comparison with the next fastest JS projects using the benchmark tool from msgpack-lite (and the sample data is from some clinical research data we use that has a good mix of different value types and structures). It also includes comparison to V8 native JSON functionality, and JavaScript Avro (avsc, a very optimized Avro implementation):

operation	op	ms	op/s
buf = Buffer(JSON.stringify(obj));	75900	5003	15170
obj = JSON.parse(buf);	90800	5002	18152
require("msgpackr").pack(obj);	158400	5000	31680
require("msgpackr").unpack(buf);	99200	5003	19828
msgpackr w/ shared structures: packr.pack(obj);	183400	5002	36665
msgpackr w/ shared structures: packr.unpack(buf);	415000	5000	83000
buf = require("msgpack-lite").encode(obj);	30600	5005	6113
obj = require("msgpack-lite").decode(buf);	15900	5030	3161
buf = require("@msgpack/msgpack").encode(obj);	101200	5001	20235
obj = require("@msgpack/msgpack").decode(buf);	71200	5004	14228
buf = require("msgpack5")().encode(obj);	8100	5041	1606
obj = require("msgpack5")().decode(buf);	14000	5014	2792
buf = require("notepack").encode(obj);	65300	5006	13044
obj = require("notepack").decode(buf);	32300	5001	6458
require("avsc")...make schema/type...type.toBuffer(obj);	86900	5002	17373
require("avsc")...make schema/type...type.fromBuffer(obj);	106100	5000	21220

All benchmarks were performed on Node 14.8.0 (Windows i7-4770 3.4Ghz). (avsc is schema-based and more comparable in style to msgpackr with shared structures).

Here is a benchmark of streaming data (again borrowed from msgpack-lite's benchmarking), where msgpackr is able to take advantage of the structured record extension and really demonstrate its performance capabilities:

operation (1000000 x 2)	op	ms	op/s
new PackrStream().write(obj);	1000000	372	2688172
new UnpackrStream().write(buf);	1000000	247	4048582
stream.write(msgpack.encode(obj));	1000000	2898	345065
stream.write(msgpack.decode(buf));	1000000	1969	507872
stream.write(notepack.encode(obj));	1000000	901	1109877
stream.write(notepack.decode(buf));	1000000	1012	988142
msgpack.Encoder().on("data",ondata).encode(obj);	1000000	1763	567214
msgpack.createDecodeStream().write(buf);	1000000	2222	450045
msgpack.createEncodeStream().write(obj);	1000000	1577	634115
msgpack.Decoder().on("data",ondata).decode(buf);	1000000	2246	445235

See the benchmark.md for more benchmarks and information about benchmarking.

Custom Extensions

You can add your own custom extensions using by using the addExtension function:

import { addExtension } from 'msgpackr'

class MyCustomClass {...}

addExtension({
	Class: MyCustomClass,
	type: 11, // register our own extension code (a type code from 0-127)
	pack(instance) {
		// define how your custom class should be encoded
		return Buffer.from(instance.someString)
	}
	unpack(buffer) {
		// define how your custom class should be decoded
		let instance = new MyCustomClass()
		instance.someString = buffer.toString()
		return instance
	}
})

Additional Performance Optimizations

Msgpackr is already fast, but here are some tips for making it faster:

Buffer Reuse

Msgpackr is designed to work well with reusable buffers. Allocating new buffers can be relatively expensive, so if you have Node addons, it can be much faster to reuse buffers and use memcpy to copy data into existing buffers. Then msgpackr unpack can be executed on the same buffer, with new data, and optionally take a second paramter indicating the effective size of the available data in the buffer.

Arena Allocation (resetMemory())

During the serialization process, data is written to buffers. Again, allocating new buffers is a relatively expensive process, and the resetMemory method can help allow reuse of buffers that will further improve performance. The resetMemory method can be called when previously created buffer(s) are no longer needed. For example, if we serialized an object, and wrote it to a database, we could indicate that we are done:

let buffer = packr.pack(data);
writeToStorageSync(buffer);
// finished with buffer, we can reset the memory on our packr now:
packr.resetMemory()
// future serialization can now reuse memory for better performance

The use of resetMemory is never required, buffers will still be handled and cleaned up through GC if not used, it just provides a small performance boost.

Record Structure Extension Definition

The record struction extension uses extension id 0x72 ("r") to declare the use of this functionality. The extension "data" byte (or bytes) identifies the byte or bytes used to identify the start of a record in the subsequent MessagePack block or stream. The identifier byte (or the first byte in a sequence) must be from 0x40 - 0x7f (and therefore replaces one byte representations of positive integers 64 - 127, which can alternately be represented with int or uint types). The extension declaration must be immediately follow by an MessagePack array that defines the field names of the record structure.

Once a record identifier and record field names have been defined, the parser/decoder should proceed to read the next value. Any subsequent use of the record identifier as a value in the block or stream should parsed as a record instance, and the next n values, where is n is the number of fields (as defined in the array of field names), should be read as the values of the fields. For example, here we have defined a structure with fields "foo" and "bar", with the record identifier 0x40, and then read a record instance that defines the field values of 4 and 2, respectively:

+--------+--------+--------+~~~~~~~~~~~~~~~~~~~~~~~~~+--------+--------+--------+
|  0xd4  |  0x72  |  0x40  | array: [ "foo", "bar" ] |  0x40  |  0x04  |  0x02  |
+--------+--------+--------+~~~~~~~~~~~~~~~~~~~~~~~~~+--------+--------+--------+

Which should generate an object that would correspond to JSON:

{ "name" : 4, "bar": 2}

Additional value types

msgpackr supports undefined (using fixext1 + type: 0 + data: 0 to match other JS implementations), NaN, Infinity, and -Infinity (using standard IEEE 754 representations with doubles/floats).

Dates

msgpackr saves all JavaScript Dates using the standard MessagePack date extension (type -1), using 32-bit if useTimestamp32 options is specified or 64-bit or 96-bit depending on the date.

License

MIT

Credits

Various projects have been inspirations for this, and code has been borrowed from https://github.com/msgpack/msgpack-javascript and https://github.com/mtth/avsc.