nodejs测试： buffer和字符串相加对比测试

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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

/usr/mytools/httpd/bin/ab -c 300 -n 10000 http://127.0.0.1:1340

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 <$Revision: 655654 {1}gt;Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/Licensed to The Apache Software Foundation, http://www.apache.org/Benchmarking 127.0.0.1 (be patient)Completed 1000 requestsCompleted 2000 requestsCompleted 3000 requestsCompleted 4000 requestsCompleted 5000 requestsCompleted 6000 requestsCompleted 7000 requestsCompleted 8000 requestsCompleted 9000 requestsCompleted 10000 requestsFinished 10000 requestsServer Software:        Server Hostname:        127.0.0.1Server Port:            1339Document Path:          /Document Length:        16384 bytesConcurrency Level:      300Time taken for tests:   3.602 secondsComplete requests:      10000Failed requests:        0Write errors:           0Total transferred:      164220000 bytesHTML transferred:       163840000 bytesRequests per second:    2776.02 [#/sec] (mean)Time per request:       108.068 [ms] (mean)Time per request:       0.360 [ms] (mean, across all concurrent requests)Transfer rate:          44519.36 [Kbytes/sec] receivedConnection Times (ms)              min  mean[+/-sd] median   maxConnect:        0   36 326.6      0    3008Processing:     1   47  29.8     46     570Waiting:        1   47  29.8     46     570Total:          1   83 328.9     46    3094Percentage of the requests served within a certain time (ms)  50%     46  66%     60  75%     68  80%     72  90%     81  95%     90  98%    141  99%   3033 100%   3094 (longest request)madding@wmmad:~$ /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 requestsCompleted 2000 requestsCompleted 3000 requestsCompleted 4000 requestsCompleted 5000 requestsCompleted 6000 requestsCompleted 7000 requestsCompleted 8000 requestsCompleted 9000 requestsCompleted 10000 requestsFinished 10000 requestsServer Software:        Server Hostname:        127.0.0.1Server Port:            1340Document Path:          /Document Length:        16384 bytesConcurrency Level:      300Time taken for tests:   1.167 secondsComplete requests:      10000Failed requests:        0Write errors:           0Total transferred:      164220000 bytesHTML transferred:       163840000 bytesRequests 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] receivedConnection Times (ms)              min  mean[+/-sd] median   maxConnect:        0    0   0.9      0       9Processing:     0   16  12.5     15     611Waiting:        0   15  12.4     15     610Total:          1   16  12.5     15     612Percentage 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。