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Buffer performance degradation in 6.6.0 #8733
Description
When comparing 6.6.0 against 6.5.0 using one of our benchmarks, we’ve noticed that there’s a performance degradation in the buffer code. We’re running a benchmark that creates a new buffer from an array as many times as it can over a given period of time, for example -
var ARRAY = [1, 2, 23829, 4, 5, 7, 12312321, 2131, 434832, 43792, 23421, 65345, 132210, 77777, 322131, 1, 2, 23829, 4, 5, 7, 12312321, 2131, 434832, 43792, 23421, 65345, 132210, 77777, 322131, 1, 2, 23829, 4, 5, 7, 12312321, 2131, 434832, 43792, 23421, 65345, 132210, 77777, 322131, 1, 2, 23829, 4, 5, 7, 12312321, 2131, 434832, 43792, 23421, 65345, 132210, 77777, 322131];
var ITERATIONS = 300000;
var result;
function test() {
for(var i=0;i<ITERATIONS;i++) {
result = new Buffer(ARRAY);
}
}On 6.6.0 there an approx 10% slowdown over 6.5.0. Been working through the likely reasons with @gareth-ellis and found that this appears to have been caused by PR #8453 where in buffer.js instances of
if (value instanceof ArrayBuffer)
have been changed to
if (isArrayBuffer(value))
We saw this regression on Linux PPC64, however, if we back this change out of 6.6.0 and rebuild on both Linux PPC64 and Linux Intel, then we see a performance increase, suggesting that the change is having an adverse affect on buffer performance.
Activity
addaleax commentedon Sep 23, 2016
I’ll look into this. I assume the overhead comes from the explicit call into C++, so it trades of correctness for performance; I guess this particular case could be easily improved with an
Array.isArray()shortcut, but I’ll try to make theBufferbenchmarking suite a bit more comprehensive to get an accurate picture of howBuffer.from()performs.addaleax commentedon Sep 23, 2016
Benchmark PR for
Buffer.from(): #8738trevnorris commentedon Sep 23, 2016
I threw up a branch w/ a commit that should gain back that performance issue: trevnorris@e555b5a
not putting that in a PR just yet because it doesn't fix the actual problem. was just able to find performance elsewhere that was lying around.
addaleax commentedon Sep 23, 2016
btw, #8739 touches the same code, so you may want to comment there too, once you know more?
Fishrock123 commentedon Sep 26, 2016
fix is in #8754 I think?
addaleax commentedon Sep 26, 2016
No, that is a distinct performance regression –#8754 fixes a performance regression that comes with the V8 5.4 upgrade, nothing that’s released yet.
benchmark: add benchmarks for `Buffer.from()`
benchmark: add benchmarks for `Buffer.from()`
Trott commentedon Jul 10, 2017
Is this still an issue?
apapirovski commentedon Apr 11, 2018
I'm going to go ahead and close given the lack of any updates or movement in over a year.