[RESOLVED] Executing an application from PHP

Sekiryou

System:
[INDENT]Windows XP Pro
Service Pack 3 / .Net 3.5
Apache 2.2.11
PHP 5.2.9-2[/INDENT]

Hi,
In a website project I have to convert mathematical formulas into .png images with LaTeX in my PHP code. The problem I have is that when I call LaTeX from PHP, the program takes for ever to execute and PHP crash after the timeout have been reached.

PHP Fatal error: Maximum execution time of 30 seconds exceeded in C:\WWW\lc.workspace.com\site\index.php on line 44

And this, even if everything went normally without any error with latex.exe. However, in command line, this process takes a fraction of a second to execute without any error too.

My homework so far:

Like suggested in another forum, I have added this to my php file:

ini_set("max_execution_time", "240");

to "remove" the timeout error. It worked. But the process takes 2 minutes 47 secondes to execute. This takes too much time since latex.exe can be called several times in a single page to generate multiple mathematical formulas. I have tried thoses commands, exec(), shell_exec(), popen()/pclose(), system(), all of them without any success. Here is some exemples I've tried:

exec($command);
exec($command . " >NUL");
exec("start /B " . $command);
shell_exec($command);
pclose(popen("start ". $command, "r"));

$output = array();
$result = null;
$return = exec($command, $output, $result);
or
exec('start /B "'.$command.'"', $output, $return);

and many other I don't remember. It's always the same result and latex.exe takes 2 min 40 sec or so to execute from PHP.

Once the timeout problem resolved, I don't have any error in the Apache logs.

In php.ini, safe_mode is Off and disable_functions is Off like suggested elsewhere.

I have tried some simple commands to test for permissions, like "dir ." and "copy from to"... Every things works fine, with the dir command, the folder is listed in the output array. With the copy command, the file is copied and I have the message "1 file(s) copied." in the array. All of these tests with other command went fine and took a fraction of a second to execute.

I had the idea to look what was going on in the windows task manager to see what is happening. It's weird, when I execute latex.exe through PHP, the processor usage goes up to 90% to 100% during 2 minutes 40 secondes or so, until the process stop and then everything comes back to normal. When I do the same command in command line, I can't even see the process in the task manager, it's too fast. And CPU usage doesn't even budge. This isn't normal?

So here I am... I'm a bit lost now.

Thanks for your help and suggestions.
Sébastien.

wjgilmore

Hi Sébastien,

The problem you are encountering is actually not related to PHP, but rather to the fact that functions such as exec(), shell_exec(), popen()/pclose(), and system() are not supported by the Windows operating system. If you move your code over to a shared web host running Linux or other Unix variant, these commands will work just fine.

Hope this helps!
Jason

==
W. Jason Gilmore
http://www.easyphpwebsites.com/

Sekiryou

wjgilmore;10918028 wrote:
[...] functions such as [...] are not supported by the Windows operating system.

But i'm able to start any kind off applications... I have this problem with only one or two application that "hangs" and work really slowly for some reason. When I redirect the output to a text file, I look at it with an editor that updates itself the file and I have a new line (not even complete) every 10 or 15 secondes. It's like the application was running on an old i486 computer. :p

Anyway, do you know if there is any alternative for windows environment? Other people seems to have find a way because I have seen some website hosted on windows operating systems that are able to do what I want...

wjgilmore;10918028 wrote:
If you move your code over to a shared web host running Linux or other Unix variant, these commands will work just fine.

The problem is that I can't... Because we own our webserver. :queasy:

Thanks for your reply.

dagon

just an i idea:

I think windows has a way of prioritising foreground vs background tasks, i think as the app is being launched in the background it is be given very little resources to work with.

could be completely wrong (never run php on windows), but may be worth a look.

Sekiryou

dagon;10918052 wrote:
just an i idea:

I think windows has a way of prioritising foreground vs background tasks, i think as the app is being launched in the background it is be given very little resources to work with.

could be completely wrong (never run php on windows), but may be worth a look.

This is not a bad idea. But I don't think it is that... I have run the process via PHP in foreground (the windows pops up in my face) and still, it takes alot of time to execute. But your reply made me test something, i've tried to execute the PHP script directly from the command line (C:\WWW\workspace.com\site>php index.php) and guess what !? Everything goes fine and latex.exe is executed in a fraction of a second. Could it be Apache blocking the execution of the program??

rsmith

It could be that the user running apache on your windows machines has insufficient rights. I've been able to use exec() to run programs from a windows host system. It's how I test scripts before modifying them for clients. I think the trick with exec() on windows systems is you have to use the windows path convention and may have to use double \s because \ in PHP is an escape character. For example:

exec("c:\\path\\to\\executable\\convert 'image.jpg' -resize 100x100! 'image.jpg'");

Works on a Windows host.

Sekiryou

rsmith;10918063 wrote:
It could be that the user running apache on your windows machines has insufficient rights. I've been able to use exec() to run programs from a windows host system. It's how I test scripts before modifying them for clients. I think the trick with exec() on windows systems is you have to use the windows path convention and may have to use double \s because \ in PHP is an escape character. For example:
exec("c:\\path\\to\\executable\\convert 'image.jpg' -resize 100x100! 'image.jpg'");
Works on a Windows host.

Thanks for your reply.

I have tried with "\", it's exactly the same result. Windows is now compatible with path using "/"... I don't know since when... but I have tried it with the command line (cmd.exe) and both work fine.

It's funny that you are using "convert.exe" as an example... because convert.exe works fine on my web server. I only have problem executing "latex.exe" and "dvips.exe". The rest is fine.

Weedpacket

The user notes on the exec manual page suggest

pclose(popen("start /B ". $cmd, "r"));

Where $cmd is (of course) the command line to be executed. In this case

pclose(popen("start /B ". 'c:\path\to\executable\convert image.jpg -resize 100x100! image.jpg', "r"));

Note that when I tried this convert whined about not being able to find a file named 'image.jpg' when I had quotes around the file name.

Sekiryou

A little update here.

After many trials and fails, I've decided to make a little test environnement and installed EasyPHP 3.0. Just to see what would happen. Guess what, everything works perfectly. Good, so i'm on the right path.

I've started by comparing EasyPHP config files (httpd.conf and php.ini) with the original ones I was using with a file compare tool. The weird thing is that they are virtually identical (except for some variables EasyPHP use like the $path thing).

I've retested with the version of Apache and PHP that EasyPHP uses. Same problem occurs even with an identical php.ini and httpd.conf. So there must be a thing EasyPHP do that I don't !

Now, I know it's possible to make this to work because it work in EasyPHP. But I can't figure out what is different.

Does that help somebody to help me ?

Thanks
Sébastien

Sekiryou

Ok, I've seen a bunch of bug report similar to my problem on PHP.net. But it seems that PHP Team and Apache Team are throwing out the ball at each other. PHP Team say it's an Apache problem and Apache Team say it's a PHP problem!

Anyway, I've tried with a COM object but it is still the same result, the process just hang for more than 2 minutes.

Now, I was wondering what EasyPHP was doing that i'm not. Because with a 100% identical configuration files (PHP and Apache), the problem does not occurs using EasyPHP. I discovered that EasyPHP does not start Apache in Service Mode. So, I reinstalled PHP and Apache and I have made Apache start as a console application. And guess what ? The problem just vanished. The problem seems to be when Apache is started as a Windows Service. Now I have this annoying cmd.exe window in my task bar but at least, everything works according to my needs. I will probably reply on some PHP bug reports to tell them my findings. Could help someone else ! Who knows?

Thank all of you very much for your help. I think i've tried everything on that one !
Thanks again.

🆒

Sébastien.