How to Execute and Terminate Realtime PHP Processes?

Realtime Process Execution and Termination in PHP

This question explores how to execute a process on a web page and receive its output in real time, eliminating the need to wait until the process completes. The second part of the question addresses how to terminate such processes when a user leaves the page.

One method for executing processes in PHP and streaming their output is through the proc_open() function. This function allows for the creation of a child process that can run independently from the parent PHP process. To facilitate real-time output, you can specify the $descriptorspec parameter with appropriate file descriptors to capture the process's stdout and stderr streams.

$cmd = "ping 127.0.0.1";

$descriptorspec = array(
   0 => array("pipe", "r"),   // stdin is a pipe that the child will read from
   1 => array("pipe", "w"),   // stdout is a pipe that the child will write to
   2 => array("pipe", "w")    // stderr is a pipe that the child will write to
);

flush();
$process = proc_open($cmd, $descriptorspec, $pipes, realpath('./'), array());

Once the child process is created, you can use a loop to continuously read from the stdout pipe and print the output.

echo "<pre class="brush:php;toolbar:false">";
if (is_resource($process)) {
    while ($s = fgets($pipes[1])) {
        print $s;
        flush();
    }
}
echo "

";

To terminate the child process when the user leaves the page, you can use a PHP shutdown function. Shutdown functions are executed when the PHP script terminates, which can occur when a user closes a browser tab or navigates away from the page. In the shutdown function, you can call proc_close() on the child process handle to terminate it.

register_shutdown_function(function() {
  proc_close($process);
});

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