Not fast enough

[Sequoia]

root@58ad89a57202:/usr/src/app# yes | pv > /dev/null
11.5MiB 0:00:09 [1.02MiB/s] [                             <=>]

root@58ad89a57202:/usr/src/app# /usr/bin/yes | pv > /dev/null
1.07GiB 0:00:09 [ 142MiB/s] [                             <=>]

Expected

Pure JavaScript yes is the finest yes in all the land.

Actual

Gnu coreutils yes is approximately 142 times faster than Pure JavaScript yes 😭

[laduke]

For some reason, the node version speeds up if you provide a long string

[laduke]

#!/usr/bin/env node
var msg = process.argv.length > 2 ? process.argv[2] : 'y';
var Readable = require('stream').Readable

var rs = new Readable;
var c = 0;
var size = Buffer.byteLength(msg, "utf8")

msg = msg + '\r\n'

rs._read = function () {
    c++;
    rs.push(msg);
};

rs.pipe(process.stdout)


process.on('exit', function () {
  console.error('\n_read() called ' + c + ' times');
});
process.stdout.on('error', process.exit);

[akx]

#!/usr/bin/env node
var msg = (process.argv.length > 2 ? process.argv[2] : 'y') + '\r\n';
var repeatedMsg = msg.repeat(Math.max(1, Math.floor(8192 / Buffer.byteLength(msg, 'utf8'))));
var buf = Buffer.from(repeatedMsg, 'utf8');
var pump = function() {
	process.stdout.write(buf, null, pump);
};	
pump();

seems to reach ~1.85 GiB/s with a 9000 byte payload, where master reaches ~900 KiB/s. That's a 2000x speedup.

[laduke]

process.stdout._handle.setBlocking( true )

const yes = Buffer.alloc( 8192, 'y\n' ) // set to 5000000 below
const write = process.stdout.write.bind( process.stdout )

const f = () => {
    write( yes )
    setImmediate( f )
}




setImmediate( f )

https://www.reddit.com/r/programming/comments/6gxf02/how_is_gnus_yes_so_fast_xpost_runix/diu5fo7/?utm_content=permalink&utm_medium=front&utm_source=reddit&utm_name=programming