I have a process intensive task that I would like to run in the background.
The user clicks on a page, the PHP script runs, and finally, based on some conditions, if required, then it has to run a shell script, E.G.:
shell_exec('php measurePerformance.php 47 844 email#yahoo.com');
Currently I use shell_exec, but this requires the script to wait for an output. Is there any way to execute the command I want without waiting for it to complete?
How about adding.
"> /dev/null 2>/dev/null &"
shell_exec('php measurePerformance.php 47 844 email#yahoo.com > /dev/null 2>/dev/null &');
Note this also gets rid of the stdio and stderr.
This will execute a command and disconnect from the running process. Of course, it can be any command you want. But for a test, you can create a php file with a sleep(20) command it.
exec("nohup /usr/bin/php -f sleep.php > /dev/null 2>&1 &");
You can also give your output back to the client instantly and continue processing your PHP code afterwards.
This is the method I am using for long-waiting Ajax calls which would not have any effect on client side:
ob_end_clean();
ignore_user_abort();
ob_start();
header("Connection: close");
echo json_encode($out);
header("Content-Length: " . ob_get_length());
ob_end_flush();
flush();
// execute your command here. client will not wait for response, it already has one above.
You can find the detailed explanation here: http://oytun.co/response-now-process-later
On Windows 2003, to call another script without waiting, I used this:
$commandString = "start /b c:\\php\\php.EXE C:\\Inetpub\\wwwroot\\mysite.com\\phpforktest.php --passmsg=$testmsg";
pclose(popen($commandString, 'r'));
This only works AFTER giving changing permissions on cmd.exe - add Read and Execute for IUSR_YOURMACHINE (I also set write to Deny).
Use PHP's popen command, e.g.:
pclose(popen("start c:\wamp\bin\php.exe c:\wamp\www\script.php","r"));
This will create a child process and the script will excute in the background without waiting for output.
Sure, for windows you can use:
$WshShell = new COM("WScript.Shell");
$oExec = $WshShell->Run("C:/path/to/php-win.exe -f C:/path/to/script.php", 0, false);
Note:
If you get a COM error, add the extension to your php.ini and restart apache:
[COM_DOT_NET]
extension=php_com_dotnet.dll
If it's off of a web page, I recommend generating a signal of some kind (dropping a file in a directory, perhaps) and having a cron job pick up the work that needs to be done. Otherwise, we're likely to get into the territory of using pcntl_fork() and exec() from inside an Apache process, and that's just bad mojo.
That will work but you will have to be careful not to overload your server because it will create a new process every time you call this function which will run in background. If only one concurrent call at the same time then this workaround will do the job.
If not then I would advice to run a message queue like for instance beanstalkd/gearman/amazon sqs.
Related
I'm working on a web application that needs to send a lot of HTTP requests and update the table, this will block the PHP from executing. So I though I might have to write a separate PHP script and run it via my main application. I tried Exec but still the program waits until the script is executed.
exec('php do_job.php');
I even tried redirecting the output to a file as PHP.Net suggests:
Note: If a program is started with this function, in order for it to
continue running in the background, the output of the program must be
redirected to a file or another output stream. Failing to do so will
cause PHP to hang until the execution of the program ends.
$result = exec('php do_job.php > output.txt &',$output);
But still no success ... Further down the same page I came accross this:
$command = 'php do_job.php';
$shell = new COM("WScript.Shell");
$shell->run($command, 0, false);
Still no sucess ... Lastly I tried:
pclose(popen("start /B ". $command, "r"));
What am I doing wrong here?
I'm developing my app on localhost (XAMPP - Windows), later I'll be releasing it on a Linux host. My last resort would be to run the script via CRON jobs. Is this the only way?
By just adding & at the end of command you can run any command in background. Here I'm redirecting o/p to /dev/null to avoid hang(For Linux).
exec('php do_job.php > /dev/null &');
If you want see the o/p of the command you can redirect it to a file.
exec('php do_job.php > full_path_to_file &');
I want to trigger a shell command in eider exec() or system() from PHP script but it is a task that take a while to complete, is there a way to trigger it and continue running the PHP page load without delay?
Edit: I am on CentOS 6, PHP 5.3
Depends on the OS you are using.
For linux:
pclose(popen("php somefile.php &","r"));
notice the amperstand at the end (very important).
For windows:
pclose(popen("start php.exe somefile.php","r"));
here the start keyword is important.
Hope this helps.
This doesn't answer your question directly, but you should consider doing your video conversion work in a background process with either a cron job or using a queue such as Beanstalkd.
This way you can stack up your ffmpeg work in the background without blocking your webserver.
I've had a lot of success with both methods (cron / queue) in the past.
Some other posts about background processes:
php execute a background process
Run a ffmpeg process in the background
Using ffmpeg, PHP and beanstalk
Some tools you might find useful:
http://kevin.vanzonneveld.net/techblog/article/create_daemons_in_php/
PEAR System_Daemon
Pheanstalk, a Beanstalkd library for PHP
What I do:
public function post_create()
{
ob_end_clean();
header("Connection: close");
ignore_user_abort(); // optional
ob_start();
echo "Tell ajax to gtfo!";
$size = ob_get_length();
header("Content-Length: $size");
ob_end_flush(); // Strange behaviour, will not work
flush(); // Unless both are called !
// Do processing here
}
This should work:
shell_exec("nohup yourcommand > /dev/null 2> /dev/null &");
Edit: sorry, dunno why I excluded the & to put it to bg
2> redirects STDOUT and STDERR to /dev/null.
Well use an ajax request to activate the exec part ...then continue with the other tasks
For a website, I need to be able to start and stop a daemon process. What I am currently doing is
exec("sudo /etc/init.d/daemonToStart start");
The daemon process is started, but Apache/PHP hangs. Doing a ps aux revealed that sudo itself changed into a zombie process, effectively killing all further progress. Is this normal behavior when trying to start a daeomon from PHP?
And yes, Apache has the right to execute the /etc/init.d/daemonToStart command. I altered the /etc/sudoers file to allow it to do so. No, I have not allowed Apache to be able to execute any kind of command, just a limited few to allow the website to work.
Anyway, going back to my question, is there a way to allow PHP to start daemons in a way that no zombie process is created? I ask this because when I do the reverse, stopping an already started daemon, works just fine.
Try appending > /dev/null 2>&1 & to the command.
So this:
exec("sudo /etc/init.d/daemonToStart > /dev/null 2>&1 &");
Just in case you want to know what it does/why:
> /dev/null - redirect STDOUT to /dev/null (blackhole it, in other words)
2>&1 - redirect STDERR to STDOUT (blackhole it as well)
& detach process and run in the background
I had the same problem.
I agree with DaveRandom, you have to suppress every output (stdout and stderr). But no need to launch in another process with the ending '&': the exec() function can't check the return code anymore, and returns ok even if there is an error...
And I prefer to store outputs in a temporary file, instead of 'blackhole'it.
Working solution:
$temp = tempnam(sys_get_temp_dir(), 'php');
exec('sudo /etc/init.d/daemonToStart >'.$temp.' 2>&1');
Just read file content after, and delete temporary file:
$output = explode("\n", file_get_contents($temp));
#unlink($temp);
I have never tried starting a daemon from PHP, but I have tried running other shell commands, with much trouble. Here are a few things I have tried, in the past:
As per DaveRandom's answer, append /dev/null 2>&1 & to the end of your command. This will redirect errors to standard output. You can then use this output to debug.
Make sure your webserver's user's PATH contains all referenced binaries inside your daemon script. You can do this by calling exec('echo $PATH; whoami;). This will tell you the user PHP is running under, and it's current PATH variable.
I'm looking for the best, or any way really to start a process from php in the background so I can kill it later in the script.
Right now, I'm using: shell_exec($Command);
The problem with this is it waits for the program to close.
I want something that will have the same effect as nohup when I execute the shell command. This will allow me to run the process in the background, so that later in the script it can be closed. I need to close it because this script will run on a regular basis and the program can't be open when this runs.
I've thought of generating a .bat file to run the command in the background, but even then, how do I kill the process later?
The code I've seen for linux is:
$PID = shell_exec("nohup $Command > /dev/null & echo $!");
// Later on to kill it
exec("kill -KILL $PID");
EDIT: Turns out I don't need to kill the process
shell_exec('start /B "C:\Path\to\program.exe"');
The /B parameter is key here.
I can't seem to find where I found this anymore. But this works for me.
Will this function from the PHP Manual help?
function runAsynchronously($path,$arguments) {
$WshShell = new COM("WScript.Shell");
$oShellLink = $WshShell->CreateShortcut("temp.lnk");
$oShellLink->TargetPath = $path;
$oShellLink->Arguments = $arguments;
$oShellLink->WorkingDirectory = dirname($path);
$oShellLink->WindowStyle = 1;
$oShellLink->Save();
$oExec = $WshShell->Run("temp.lnk", 7, false);
unset($WshShell,$oShellLink,$oExec);
unlink("temp.lnk");
}
Tried to achieve the same on a Windows 2000 server with PHP 5.2.8.
None of the solutions worked for me. PHP kept waiting for the response.
Found the solution to be :
$cmd = "E:\PHP_folder_path\php.exe E:\some_folder_path\backgroundProcess.php";
pclose(popen("start /B ". $cmd, "a")); // mode = "a" since I had some logs to edit
From the php manual for exec:
If a program is started with this function, in order for it to continue running in the background, the output of the program must be redirected to a file or another output stream. Failing to do so will cause PHP to hang until the execution of the program ends.
ie pipe the output into a file and php won't wait for it:
exec('myprog > output.txt');
From memory, I believe there is a control character that you can prepend (like you do with #) to the exec family of commands that also prevents execution from pausing - can't remember what it is though.
Edit Found it! On unix, programs executed with & prepended will run in the background. Sorry, doesn't help you much.
On my Windows 10 and Windows Server 2012 machines, the only solution that worked reliably within pclose/popen was to invoke powershell's Start-Process command, as in:
pclose(popen('powershell.exe "Start-Process foo.bat -WindowStyle Hidden"','r'));
Or more verbosely if you want to supply arguments and redirect outputs:
pclose(popen('powershell.exe "Start-Process foo.bat
-ArgumentList \'bar\',\'bat\'
-WindowStyle Hidden
-RedirectStandardOutput \'.\\console.out\'
-RedirectStandardError \'.\\console.err\'"','r'));
I have a process intensive task that I would like to run in the background.
The user clicks on a page, the PHP script runs, and finally, based on some conditions, if required, then it has to run a shell script, E.G.:
shell_exec('php measurePerformance.php 47 844 email#yahoo.com');
Currently I use shell_exec, but this requires the script to wait for an output. Is there any way to execute the command I want without waiting for it to complete?
How about adding.
"> /dev/null 2>/dev/null &"
shell_exec('php measurePerformance.php 47 844 email#yahoo.com > /dev/null 2>/dev/null &');
Note this also gets rid of the stdio and stderr.
This will execute a command and disconnect from the running process. Of course, it can be any command you want. But for a test, you can create a php file with a sleep(20) command it.
exec("nohup /usr/bin/php -f sleep.php > /dev/null 2>&1 &");
You can also give your output back to the client instantly and continue processing your PHP code afterwards.
This is the method I am using for long-waiting Ajax calls which would not have any effect on client side:
ob_end_clean();
ignore_user_abort();
ob_start();
header("Connection: close");
echo json_encode($out);
header("Content-Length: " . ob_get_length());
ob_end_flush();
flush();
// execute your command here. client will not wait for response, it already has one above.
You can find the detailed explanation here: http://oytun.co/response-now-process-later
On Windows 2003, to call another script without waiting, I used this:
$commandString = "start /b c:\\php\\php.EXE C:\\Inetpub\\wwwroot\\mysite.com\\phpforktest.php --passmsg=$testmsg";
pclose(popen($commandString, 'r'));
This only works AFTER giving changing permissions on cmd.exe - add Read and Execute for IUSR_YOURMACHINE (I also set write to Deny).
Use PHP's popen command, e.g.:
pclose(popen("start c:\wamp\bin\php.exe c:\wamp\www\script.php","r"));
This will create a child process and the script will excute in the background without waiting for output.
Sure, for windows you can use:
$WshShell = new COM("WScript.Shell");
$oExec = $WshShell->Run("C:/path/to/php-win.exe -f C:/path/to/script.php", 0, false);
Note:
If you get a COM error, add the extension to your php.ini and restart apache:
[COM_DOT_NET]
extension=php_com_dotnet.dll
If it's off of a web page, I recommend generating a signal of some kind (dropping a file in a directory, perhaps) and having a cron job pick up the work that needs to be done. Otherwise, we're likely to get into the territory of using pcntl_fork() and exec() from inside an Apache process, and that's just bad mojo.
That will work but you will have to be careful not to overload your server because it will create a new process every time you call this function which will run in background. If only one concurrent call at the same time then this workaround will do the job.
If not then I would advice to run a message queue like for instance beanstalkd/gearman/amazon sqs.