Small optimization for parseUnsignedNumber

[dougwilson]

This implements a small optimization for the parseUnsignedNumber method in the parser. This method is called multiple times for parsing almost all packets, making a gain here seem like it would be pretty nice. Checking out a simple test on jsperf it seems like it would make this method about 3x faster than what it is now. I cannot say if this actually has any real-world performance impacts yet, though.

[sidorares]

a lot of failed tests

[dougwilson]

Yea, looks like I made a logic error in the offset calculation.

[dougwilson]

OK, code is corrected and tests are passing.

[sidorares]

lgtm, but I'll wait for benchmark (it's 2 hours wrk load test)

[dougwilson]

No problem. Obviously I'm only interested in the patch if it actually makes any real difference, since it is an optimization :)

[felixge]

Just ran this through my faster than c benchmark (heavy row data parsing): https://docs.google.com/spreadsheet/ccc?key=0ApjTSpxgQIZtdFZRcXpiNUFMck5uZFlBX1lObkJnTWc&usp=sharing

Seems like your patch makes things a little faster. That being said, I only ran the benchmarks once, and my computer had a few other things running : ). Looking to hear from @sidorares .

[dougwilson]

Thanks, @felixge :)

Right now I'm actually going to say to hold off on merging this for the time being. There is another spot that can have a simple change that would also have an additional improvement like this, but more importantly, I need to be sure this change works the same as the old all the way up to the max 4 byte value.

[sidorares]

My benchmarks:

npm/2.0rc2

~/wrk$ ./wrk -t6 -c100 -d100m http://******/test
Running 100m test @ http://*****/test
  6 threads and 100 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency     9.15s     1.95s   10.80s    95.70%
    Req/Sec     2.19      3.31    27.00     95.40%
  89585 requests in 100.01m, 2.00GB read
  Socket errors: connect 0, read 0, write 0, timeout 211197
Requests/sec:     14.93
Transfer/sec:    348.82KB

dougwilson:parse-unsigned-optimization

ubuntu@ip-172-31-27-190:~/wrk$ ./wrk -t6 -c100 -d100m http://****/test
Running 100m test @ http://****/test
  6 threads and 100 connections

  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency    11.24s     3.50s   14.66s    94.73%
    Req/Sec     2.38      3.69    30.00     95.68%
  94334 requests in 100.01m, 2.10GB read
  Socket errors: connect 0, read 0, write 0, timeout 209034
Requests/sec:     15.72
Transfer/sec:    367.32KB
ubuntu@ip-172-31-27-190:~/wrk$

test setup - 3 Amazon VMs in the same subnet, 2 t1.micro (server + load test client) + db.t1.micro MySQL RDS

mysql> show create table users;
+--------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table  | Create Table                                                                                                                                                                         |
+--------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| users | CREATE TABLE `users` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=10001 DEFAULT CHARSET=latin1 |
+--------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.02 sec)

mysql> select * from users limit 100,5;
+-----+------+
| id  | name |
+-----+------+
| 101 | 101  |
| 102 | 102  |
| 103 | 103  |
| 104 | 104  |
| 105 | 105  |
+-----+------+
5 rows in set (0.00 sec)

10000 rows total.

Server under benchmark - t1.micro

//var mysql = require('mysql2');
//var mysql = require('mysql-dougwilson');
var mysql = require('mysql');

var connection = mysql.createPool({
  host     : 'db.id.ap-southeast-2.rds.amazonaws.com',
  user     : '****',
  password : '****',
  port     : '3306',
  database : '****',
  connectionLimit: 20,
  queueLimit: 1024000,
});

require('http').createServer(function(req, res) {
  if (req.url != '/test') {
    return res.end('');
  }
  connection.query('select * from users limit 1000', function(err, rows) {
    res.end(JSON.stringify(rows));
  });
}).listen(80);

Benchmark results with node-mysql2

ubuntu@ip-172-31-27-190:~/wrk$ ./wrk -t6 -c400 -d2h http://*****/test
Running 120m test @ http://*****/test
  6 threads and 400 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency    21.36s     9.60s   38.01s    70.09%
    Req/Sec     4.63      6.39    43.00     91.03%
  218841 requests in 120.01m, 4.89GB read
  Socket errors: connect 0, read 85, write 0, timeout 1210546
Requests/sec:     30.39
Transfer/sec:    711.63KB

[dougwilson]

Thanks, @sidorares :) As an update, I have moved this to #702 which implements the parseUnsignedNumber correctly and also updates parseLengthCodedNumber.