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：

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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

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代码：

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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)

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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。

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