require和require_once经济性能对比

require和require_once都是PHP函数，开发人员可以使用它们在某个特定的脚本中导入外部PHP文件。你可以根据应用程序的复杂度调用一次或若干次require_once/require。使用require（而不是require_once）可以提高应用程序的性能。

测试前准备：

创建4个空的类来模拟主脚本要使用的外部PHP文件脚本。

ClassA.php：

<?php

class ClassA
{

}

ClassB.php：

<?php

class ClassB
{

}

ClassC.php：

<?php

class ClassC
{

}

ClassD.php：

<?php

class ClassD
{

}

使用require_once导入外部文件：

index.php：

<?php

require_once './ClassA.php';
require_once './ClassB.php';
require_once './ClassC.php';
require_once './ClassD.php';

echo "Only testing require_once";

重启服务器，使用ab压力测试工具模拟10000个请求，同一时间有5个并发请求。

ab.exe -c 5 -n 10000 http://www.demo.com/optimization/index.php

测试结果：

D:phpStudyApachein>ab.exe -c 5 -n 10000 http://www.demo.com/optimization/index.php
This is ApacheBench, Version 2.3 <$Revision: 1748469 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking www.demo.com (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:        Apache/2.4.23
Server Hostname:        www.demo.com
Server Port:            80

Document Path:          /optimization/index.php
Document Length:        25 bytes

Concurrency Level:      5
Time taken for tests:   17.446 seconds
Complete requests:      10000
Failed requests:        0
Total transferred:      2280000 bytes
HTML transferred:       250000 bytes
Requests per second:    573.20 [#/sec] (mean)
Time per request:       8.723 [ms] (mean)
Time per request:       1.745 [ms] (mean, across all concurrent requests)
Transfer rate:          127.63 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0    0   0.4      0       2
Processing:     2    8  90.4      4    2503
Waiting:        1    7  90.5      3    2503
Total:          2    8  90.4      4    2504

Percentage of the requests served within a certain time (ms)
  50%      4
  66%      5
  75%      5
  80%      5
  90%      5
  95%      5
  98%      6
  99%      6
 100%   2504 (longest request)

使用ab工具测试require_once，可以看到相应时间是8.723ms，该脚本每秒支持573.20个请求。

使用require导入外部文件：

index_1.php：

<?php

require './ClassA.php';
require './ClassB.php';
require './ClassC.php';
require './ClassD.php';

echo "Only testing require";

重启服务器，使用ab压力测试工具模拟10000个请求，同一时间有5个并发请求。

ab.exe -c 5 -n 10000 http://www.demo.com/optimization/index_1.php

测试结果：

D:phpStudyApachein>ab.exe -c 5 -n 10000 http://www.demo.com/optimization/index_1.php
This is ApacheBench, Version 2.3 <$Revision: 1748469 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking www.demo.com (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:        Apache/2.4.23
Server Hostname:        www.demo.com
Server Port:            80

Document Path:          /optimization/index_1.php
Document Length:        20 bytes

Concurrency Level:      5
Time taken for tests:   17.207 seconds
Complete requests:      10000
Failed requests:        0
Total transferred:      2230000 bytes
HTML transferred:       200000 bytes
Requests per second:    581.16 [#/sec] (mean)
Time per request:       8.604 [ms] (mean)
Time per request:       1.721 [ms] (mean, across all concurrent requests)
Transfer rate:          126.56 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0    0   0.4      0      21
Processing:     1    8  86.5      4    2320
Waiting:        1    7  86.5      3    2320
Total:          1    8  86.5      4    2320

Percentage of the requests served within a certain time (ms)
  50%      4
  66%      5
  75%      5
  80%      5
  90%      5
  95%      6
  98%      7
  99%      7
 100%   2320 (longest request)

D:phpStudyApachein>ab.exe -c 5 -n 10000 http://www.demo.com/optimization/index_1.php
This is ApacheBench, Version 2.3 <$Revision: 1748469 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking www.demo.com (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

使用ab工具测试require，可以看到相应时间是8.604ms，该脚本每秒支持581.16个请求。