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V8 serialize is not deterministic #2448
Description
- node version v10.17.0:
- Linux 4.19.19-041919-lowlatency #201901310331 SMP PREEMPT Thu Jan 31 08:37:07 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux:
- npm version:
{ npm: '6.12.0',
ares: '1.15.0',
brotli: '1.0.7',
cldr: '35.1',
http_parser: '2.8.0',
icu: '64.2',
modules: '64',
napi: '5',
nghttp2: '1.39.2',
node: '10.17.0',
openssl: '1.1.1d',
tz: '2019a',
unicode: '12.1',
uv: '1.28.0',
v8: '6.8.275.32-node.54',
zlib: '1.2.11' }
v8.serialize produce different output, still decodable but it's different bytes, and different length. it's matter for me.
same PC, same version.
just want to know: what cause that difference and how to avoid it.
const v8 = require('v8');
let data = {
key: 'value',
arrValue: [1,2,3,4],
objValue: {
nestedKey: 'value'
}
};
const buffData = v8.serialize(data);
const dataCopy = v8.deserialize(buffData);
// it seems we still have same object
console.log(JSON.stringify(dataCopy) === JSON.stringify(data));
// but encoded buffer is different!
const buffEncoded = v8.serialize(Object.assign({}, dataCopy));
console.log(buffData.length !== buffEncoded.length);
console.log(buffData.toString('hex'));
console.log(buffEncoded.toString('hex'));
Activity
trueshura commentedon Jan 28, 2020
If you remove array element - it works like a charm again!
i mean
encodes as expected
addaleax commentedon Jan 28, 2020
V8 uses different internal representations for some values, for example,
Arrays in V8 can be dense or sparse, with special cases for integer arrays or floating-point-value arrays, and strings can have different internal representations as well, e.g. using UTF16 encoding or using ISO-8859-1.Generally, you can’t rely on the exact output from
v8.serialize(), that’s correct. If it’s important to you to have deterministic output, it might not be the right tool for you.trueshura commentedon Jan 28, 2020
it's ok, but i didn't expect diffrent output for "same" values.
doc: clarify that `v8.serialize()` is not deterministic
doc: clarify that `v8.serialize()` is not deterministic
doc: clarify that `v8.serialize()` is not deterministic
doc: clarify that `v8.serialize()` is not deterministic
doc: clarify that `v8.serialize()` is not deterministic
doc: clarify that `v8.serialize()` is not deterministic