PHP set_time_limit(0) function to implement long connection explanation_PHP tutorial

Every time we access a PHP script, we only get the return result after all PHP scripts have been executed. If we need a script to run continuously, then we have to use PHP long connection to achieve the purpose of running.

Each PHP script has a limited execution time, so we need to set the execution time of a script to unlimited through set_time_limit; then use flush() and ob_flush() to clear the server buffer and output the script at any time return value.

Such as the following script:
header("Content-Type: text/plain");
set_time_limit(0);

$ infoString = "Hello World" . " ";
while( isset($infoString) )
{
echo $infoString;
flush();
ob_flush();
sleep(5);
}
?>

When we execute, we will get a line of Hello World every 5 seconds. If we do not press the stop button, the browser will continue to load line by line
.
Through this method, we can complete many functions, such as robot crawlers, instant message boards and other programs