<?php if(function_exists('date_default_timezone_set')) { date_default_timezone_set('PRC'); } function a() { $time = time(); sleep(3); $fp = fopen('result_a'.$time.'.log', 'w'); fputs($fp, 'Set in ' . Date('h:i:s', time()) . (double)microtime() . "rn"); fclose($fp); } function b() { $time = time(); sleep(3); $fp = fopen('result_b'.$time.'.log', 'w'); fputs($fp, 'Set in ' . Date('h:i:s', time()) . (double)microtime() . "rn"); fclose($fp); } if(!isset($_GET['act'])) $_GET['act'] = 'a'; if($_GET['act'] == 'a') { a(); } else if($_GET['act'] == 'b') b(); ?>
以上代码，在本地写入一个文件。
如果你访问 localhost/a.php 在两个浏览器标签尽可能快的同时打开，发现两个文件创建时间相差为3秒
但是如果你访问localhost/a.php?act=b 另一个访问/a.php?act=a 你发现两个文件创建的时间几乎差不多。
对于apache来说同样的url意味着一个线程（我们或者说是进程），但是不同的URL意味着可以 并发 。
如果php内部有下载的动作
function runThread() { down("http://localhost/test/a.php?act=a"); } if($_GET['act'] == 'run') { echo 'start:'; runThread(); echo ' End'; }
http://localhost/test/a.php?act=run
http://localhost/test/a.php?act=run&s=2
只要主访问的url不同，则认为是不同的进行，意味着并发。文件创建时间不为3秒
本地有Linux服务器的朋友也可以借助linux来进行模拟并发
<?php for ($i=0;$i<10;$i++) { echo $i; sleep(5); } ?>
上面存成test.php, 然后写一段SHELL代码
#!/bin/bash
for i in 1 2 3 4 5 6 7 8 9 10
do
php -q test.php &
done
Fixed a bug where :doc:`Image Manipulation Library <libraries/image_lib>` didn't escape image source paths passed to ImageMagick as shell arguments.
Fixed a bug (#861) - :doc:`Database Forge <database/forge>` method create_table() incorrectly accepts field width constraints for mssql/SQLSRV integer-type columns.
Fixed a bug (#4562) - :doc:`Cache Library <libraries/caching>` didn't check if Memcached::quit() is available before calling it.
Fixed a bug (#4563) - :doc:`Input Library <libraries/input>` method request_headers() ignores $xss_clean parameter value after first call.
Fixed a bug (#4605) - :doc:`Config Library <libraries/config>` method site_url() stripped trailing slashes from relative URIs passed to it.
Fixed a bug (#4613) - :doc:`Email Library <libraries/config>` failed to send multiple emails via SMTP due to "already authenticated" errors when keep-alive is enabled.
Fixed a bug (#4633) - :doc:`Form Validation Library <libraries/form_validation>` ignored multiple "callback" rules for empty, non-required fields.
Fixed a bug (#4637) - :doc:`Database <database/index>` method error() returned FALSE with the 'oci8' driver if there was no error.
Fixed a bug (#4647) - :doc:`Query Builder <database/query_builder>` method count_all_results() doesn't take into account GROUP BY clauses while deciding whether to do a subquery or not.
Fixed a bug where