Multi threading in PHP

Question

In a apcahe server i want to run a PHP scripts as cron which starts a php file in background and exits just after starting of the file and doesn't wait for the script to complete as that script will take around 60 minutes to complete.how this can be done?

Answer 1

You should know that there is no threads in PHP. But you can execute programs and detach them easily if you're running on Unix/linux system.

$command = "/usr/bin/php '/path/to/your/php/to/execute.php'";
exec("{$command} > /dev/null 2>&1 & echo -n \$!");

May do the job. Let's explain a bit :

exec($command); 

Executes /usr/bin/php '/path/to/your/php/to/execute.php' : your script is launched but Apache will awaits the end of the execution before executing next code.

> /dev/null

will redirect standard output (ie. your echo, print etc) to a virtual file (all outputs written in it are lost).

2>&1

will redirect error output to standard output, writting in the same virtual and non-existing file. This avoids having logs into your apache2/error.log for example.

&

is the most important thing in your case : it will detach your execution of $command : so exec() will immediatly release your php code execution.

echo -n \$!

will give PID of your detached execution as response : it will be returned by exec() and makes you able to work with it (such as, put this pid into a database and kill it after some time to avoid zombies).