nodejs测试： buffer和字符串相加对比测试

看到jsconf2010.pdf写的关于buffer对象和string字符串相加的对比图表。发现buffer对象响应的变化很大，眼见为实，因此证实一下：

准备：

apache ab模拟并发，编写两份代码

os: debian 6.0

cpu: Intel(R) Core(TM)2 Duo CPU E8400 @ 3.00GHz

mem: 4G

代码：

var http = require('http'), string = '', buffer='';

for(i = 0; i < 16*1024; i++) {
    string +='d';
}

var server = http.createServer(
    function(req, res) {
        res.writeHead(200);
        res.end(string, 'ascii');
    }
);

server.listen(1339, '127.0.0.1');

buffer = new Buffer(16*1024);

for(i=0; i < buffer.length; i++) {
    buffer[i] = 100;
}

var server2 = http.createServer(
    function(req, res) {
        res.writeHead(200);
        res.end(buffer);
    }
);

server2.listen(1340, '127.0.0.1');

console.log('running');

说明：定义两个监听，实现不同的字符串拼接，并监听不同的端口，方便测试。

运行：

/usr/mytools/httpd/bin/ab -c 300 -n 10000 http://127.0.0.1:1339
<pre name="code" class="html">/usr/mytools/httpd/bin/ab -c 300 -n 10000 http://127.0.0.1:1340</pre>

结果：

madding@wmmad:~$ /usr/mytools/httpd/bin/ab -c 300 -n 10000 http://127.0.0.1:1339/
This is ApacheBench, Version 2.3 <$Revision: 655654 {1}gt;
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking 127.0.0.1 (be patient)
Completed 1000 requests
Completed 2000 requests
Completed 3000 requests
Completed 4000 requests
Completed 5000 requests
Completed 6000 requests
Completed 7000 requests
Completed 8000 requests
Completed 9000 requests
Completed 10000 requests
Finished 10000 requests


Server Software:        
Server Hostname:        127.0.0.1
Server Port:            1339

Document Path:          /
Document Length:        16384 bytes

Concurrency Level:      300
Time taken for tests:   3.602 seconds
Complete requests:      10000
Failed requests:        0
Write errors:           0
Total transferred:      164220000 bytes
HTML transferred:       163840000 bytes
Requests per second:    2776.02 [#/sec] (mean)
Time per request:       108.068 [ms] (mean)
Time per request:       0.360 [ms] (mean, across all concurrent requests)
Transfer rate:          44519.36 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0   36 326.6      0    3008
Processing:     1   47  29.8     46     570
Waiting:        1   47  29.8     46     570
Total:          1   83 328.9     46    3094

Percentage of the requests served within a certain time (ms)
  50%     46
  66%     60
  75%     68
  80%     72
  90%     81
  95%     90
  98%    141
  99%   3033
 100%   3094 (longest request)
madding@wmmad:~$ /usr/mytools/httpd/bin/ab -c 300 -n 10000 http://127.0.0.1:1340/
This is ApacheBench, Version 2.3 <$Revision: 655654 {1}gt;
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking 127.0.0.1 (be patient)
Completed 1000 requests
Completed 2000 requests
Completed 3000 requests
Completed 4000 requests
Completed 5000 requests
Completed 6000 requests
Completed 7000 requests
Completed 8000 requests
Completed 9000 requests
Completed 10000 requests
Finished 10000 requests


Server Software:        
Server Hostname:        127.0.0.1
Server Port:            1340

Document Path:          /
Document Length:        16384 bytes

Concurrency Level:      300
Time taken for tests:   1.167 seconds
Complete requests:      10000
Failed requests:        0
Write errors:           0
Total transferred:      164220000 bytes
HTML transferred:       163840000 bytes
Requests per second:    8565.63 [#/sec] (mean)
Time per request:       35.024 [ms] (mean)
Time per request:       0.117 [ms] (mean, across all concurrent requests)
Transfer rate:          137368.00 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0    0   0.9      0       9
Processing:     0   16  12.5     15     611
Waiting:        0   15  12.4     15     610
Total:          1   16  12.5     15     612

Percentage of the requests served within a certain time (ms)
  50%     15
  66%     19
  75%     21
  80%     23
  90%     26
  95%     30
  98%     33
  99%     37
 100%    612 (longest request)

说明：在300个并发，10000个请求下，采用buffer方式构造对象的性能优化是和之前的3倍以上。