proc_terminate() does not terminate process even after lots of time - php

Question

I open a process using proc_open(), then usleep() for some time and after that check status of the process. If the process is still running then I proc_terminate() it.
The problem is when I use proc_terminate() the script continues without waiting for process to terminate (which is normal), but the process is not terminated even after lots of time.
The process is an .exe file which first prints hello to stdout, then enters an infinite loop.
My PHP script :
<pre>
<?php
$descriptorspec = array(
1 => array('pipe', 'w')
);
$process = proc_open("C:/wamp/www/my-project/run.exe", $descriptorspec, $pipes);
if (is_resource($process)) {
usleep(2.5*1000000); // wait 2.5 secs
$status = proc_get_status($process);
if ($status['running'] == true) {
proc_terminate($process);
echo "Terminated\n";
} else {
echo "Exited in time\n";
echo "EXIT CODE : {$status['exitcode']}\n";
echo "OUTPUT :\n";
while (!feof($pipes[1]))
echo fgets($pipes[1]);
fclose($pipes[1]);
proc_close($process);
}
}
?>
</pre>
I compile this C++ file and get the .exe :
#include <iostream>
using namespace std;
int main() {
cout << "hello";
while (1);
return 0;
}
Does anybody know why this happens? :(

Answer 1

proc_terminate() doesn't work well on Windows.
A good workaround is to call the taskkill command.
function kill($process) {
if (strncasecmp(PHP_OS, 'WIN', 3) == 0) {
$status = proc_get_status($process);
return exec('taskkill /F /T /PID '.$status['pid']);
} else {
return proc_terminate($process);
}
}

Answer 2

proc_terminate doesn't actually terminate a process, it sends a SIGTERM signal to the process asking it to terminate itself.
I think that the problem is that your test executable is not listening for the SIGTERM signal, so it is just ignored.
On POSIX systems, you can use the second parameter to send a SIGKILL, which will essentially ask the OS to terminate the process, so that might work better. On Windows, I don't know what, if anything, this would do.
But the process should be handling signals anyway. You can easily add a signal handler to your exe for testing:
#include <csignal>
#include <iostream>
#include <thread>
using namespace std;
void signal_handler(int signal)
{
cout << "received SIGTERM\n";
exit(0);
}
int main()
{
// Install a signal handler
std::signal(SIGTERM, signal_handler);
cout << "starting\n";
while (1)
std::this_thread::sleep_for(std::chrono::seconds(1));
return 0;
}
Note the addition of sleep_for also, so that the exe doesn't take 100% of the CPU.
There is also a discussion in the comments here about using posix_kill() to kill a process and its children, if the above does not work for you.