I'm currently running these lines in a PHP script:
foreach ($list as $route)
{
exec('php-cgi ./nextbus-route_stop_predictions.php route=' . $route['route_id']);
}
nextbus-route_stop_predictions.php takes about 15 seconds to run and exec() is ran about 12 times. I was wondering if PHP was able to run these those command lines without needing to wait for the output of the previous exec(). So basically, I want to run this asynchronously/multi-processes.
Update
For anyone still looking for the answer, I used nohup and piped the output to /dev/null
pcntl_fork() may be able to help if you're on *nix.
The pcntl_fork() function creates a child process that differs from the parent process only in its PID and PPID. Please see your system's fork(2) man page for specific details as to how fork works on your system.
If you are running php as an Apache module you can do the trick mentioned here
http://joseph.randomnetworks.com/archives/2005/10/21/fake-fork-in-php/
exec("php-cgi ./nextbus-route_stop_predictions.php route=" . $route['route_id'] . " 2>/dev/null >&- < &- >/dev/null &");
Basically rerouting stderr,stdout and sending the process into the background.
Related
In a apcahe server i want to run a PHP scripts as cron which starts a php file in background and exits just after starting of the file and doesn't wait for the script to complete as that script will take around 60 minutes to complete.how this can be done?
You should know that there is no threads in PHP.
But you can execute programs and detach them easily if you're running on Unix/linux system.
$command = "/usr/bin/php '/path/to/your/php/to/execute.php'";
exec("{$command} > /dev/null 2>&1 & echo -n \$!");
May do the job. Let's explain a bit :
exec($command);
Executes /usr/bin/php '/path/to/your/php/to/execute.php' : your script is launched but Apache will awaits the end of the execution before executing next code.
> /dev/null
will redirect standard output (ie. your echo, print etc) to a virtual file (all outputs written in it are lost).
2>&1
will redirect error output to standard output, writting in the same virtual and non-existing file. This avoids having logs into your apache2/error.log for example.
&
is the most important thing in your case : it will detach your execution of $command : so exec() will immediatly release your php code execution.
echo -n \$!
will give PID of your detached execution as response : it will be returned by exec() and makes you able to work with it (such as, put this pid into a database and kill it after some time to avoid zombies).
You need to use "&" symbol to run program as background proccess.
$ php -f file.php &
Thats will run this command in background.
You may wright sh script
#!/bin/bash
php -f file.php &
And run this script from crontab.
This may not be the best solution to your specific problem. But for the record, there is Threads in PHP.
https://github.com/krakjoe/pthreads
I'm assuming you know how to use threads, this is very young code that I wrote myself, but if you have experience with threads and mutex and the like you should be able to solve your problem using this extension.
This is clearly a shameless plug of my own project, and if the user doesn't have the access required to install extensions then it won't help him, but many people find stackoverflow and it will solve other problems no doubt ...
I am wanting to execute a large, database intensive script, but do not need to wait for the process to finish. I would simply like to call the script, let it run in the background and then redirect to another page.
EDIT:
i am working on a local Zend community server, on Windows 7.
I have access to remote linux servers where the project also resides, so i can do this on linux or windows.
i have this
public function createInstanceAction()
{
//calls a seperate php process which creates the instance
exec('php -f /path/to/file/createInstance.php');
Mage::getSingleton('adminhtml/session')->addSuccess(Mage::helper('adminhtml')->__('Instance creation process started. This may take up to a few minutes.'));
$this->_redirect('instances/adminhtml_instances/');
return;
}
this works perfectly, but the magento application hangs around for the process to finish. it does everything i expect, logging to file from time to time, and am happy with how its running. Now all i would like to do is have this script start, the controller action does not hang around, but instead redirects and thats that. from what I have learnt about exec(), you can do so by changing the way i call exec() above, to :
exec('php -f /path/to/file/createInstance.php > /dev/null 2>&1 &');
which i took from here
if i add "> /dev/null 2>&1 &" to the exec call, it doesnt wait around as expected, but it does not execute the script anymore. Could someone tell me why, and if so, tell me how i can get this to work please?
Could this be a permission related issue?
thanks
EDIT : Im assuming it would be an issue to have any output logged to file if i call the exec function with (/dev/null 2>&1 &) as that would cancel that. is that correct?
After taking time to fully understand my own question and the way it could be answered, i have prepared my solution.
Thanks to all for your suggestions, and for excusing my casual, unpreparedness when asking the question.
The answer to the above question depends on a number of things, such as the operating system you are referring to, which php modules you are running and even as far as what webserver you are running. So if i had to start the question again, the first thing i would do is state what my setup is.
I wanted to achieve this on two environments :
1.) Windows 7 running Zend server community edition.
2.) Linux (my OS is Linux odysseus 2.6.32-5-xen-amd64 #1 SMP Fri Sep 9 22:23:19 UTC 2011 x86_64)
to get this right, i wanted it to work either way when deploying to windows or linux, so i used php to determine what the operating system was.
public function createInstanceAction()
{
//determines what operating system is Being used
if (strtoupper(substr(PHP_OS, 0, 3)) === 'WIN')
{
//This is a windows server
//call a seperate php process to run independently from the broswer action
pclose(popen("start php /path/to/script/script.php","r"));
}
else
{
//assuming its linux, but in fact it simply means its not windows
// to check for linux specifically use (strtoupper(substr(PHP_OS, 0, 3)) === 'LIN')
exec('php -f /path/to/file/script.php >/dev/null 2>&1 &');
}
//the browser will not hang around for this process to complete, and you can contimue with whatever actions you want.
//myscript log any out put so i can capture info as it runs
}
In short, ask questions once you understand them. there are many ways to to achieve the above, and this is just one solution that works for my development and production environments.
thanks for the help all.
PHP popen
From the docs (this should help you do other stuff, while that process is working; not sure if closing the current PHP process will kill the opened process):
/* Add redirection so we can get stderr. */
$handle = popen('/path/to/executable 2>&1', 'r');
echo "'$handle'; " . gettype($handle) . "\n";
$read = fread($handle, 2096);
echo $read;
pclose($handle);
Solution 2:
Trick the browser to close the connection (assuming there is a browser involved):
ob_start();
?><html><!--example html body--></html><?php
$strContents=ob_get_clean();
header("Connection: Close");
header("Content-encoding: none");//doesn't work without this, I don't know why:(
ignore_user_abort(true);
header("Content-type: text/html");
header("Content-Length: ".strlen($strContents));
echo $strContents;
flush();
//at this point a real browser would close the connection and finish rendering;
//crappy http clients like some curl implementations (and not only) would wait for the server to close the connection, then finish rendering/serving results...:(
//TODO: add long running operations here, exec, or whatever you have.
You could write a wrapper-script, say createInstance.sh like
#! /bin/bash
trap "" SIGHUP
php -f "$1" > logfile.txt 2>&1 &
Then you call the script from within PHP:
exec('bash "/path/to/file/createInstance.sh"');
which should detach the new php process most instantly from the script. If that doesen't help, you might try to use SIGABRT, SIGTERM or SIGINT instead of SIGHUP, I don't know exactly which signal is sent.
I've been able to use:
shell_exec("nohup $command > /dev/null & echo $!")
Where $command is for example:
php script.php --parameter 1
I've noticed some strange behavior with this. For example running mysql command line doesn't work, only php scripts seem to work.
Also, running cd /path/to/dir && php nohup $command ... doesn't work either, I had to chdir() within the PHP script and then run the command for it to work.
The PHP executable included with Zend Server seems to be what's causing attempts to run a script in the background (using the ampersand & operator in the exec) to fail.
We tested this using our standard PHP executable and it worked fine. It's something to do with the version shipped with Zend Server though our limited attempts to figure out what that was going on have not turned anything up.
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 trying to setup a php trigger file that will set off a background process. (see this question)
I'm doing this on a Windows Wampserver environment.
So for example I have trigger.php that runs the exec function that calls for my backgroundProcess.php to be parsed and executed.
However the problem is that my trigger.php file is waiting for the exec() command to finish running backgroundProcess.php before it stops. The background process runs for about 20-30 seconds, and trigger.php is waiting all that time until backgroundProcess.php has fully finished.
Is that making sense? Here is the trigger.php file that runs the exec() command
exec('C:\wamp\bin\php\php'.phpversion().'\php.exe -f C:\path\to\backgroundProcess.php > C:\wamp\bin\php\php'.phpversion().'\dev\null &');
Basically, I'm wanting trigger.php to just trigger off the backgroundProcess and not wait around for it to finish.
Problem solved with the following command:
$WshShell = new COM("WScript.Shell");
$oExec = $WshShell->Run("C:\wamp\bin\php\phpVERSIONNUMBER\php-win.exe -f C:/wamp/www/path/to/backgroundProcess.php", 0, false);
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
ps :
Posting the same reply to the other thread (PHP on a windows machine; Start process in background) since these 2 links helped me a lot in doing some research on this.
From the manual : http://www.php.net/manual/en/function.exec.php
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.
And a similar question I answered : Call another PHP script and return control to user before the other script completes
You may need to change your implementation approach. Having to wait for such a long time would be an annoyance for the user of your app and fatal for the entire app.
For such tasks, it's usually better to queue the task, ideally on database, and process them periodically. There are chron jobs on Linux based systems. In Windows, you can use a scheduler to launch the backgroundProcess.php.
In addition to Rohit's answer above, I edited his solution to work on Windows 10 PHP 7.0.3:
pclose(popen("start /B ". $cmd, "w"));
It may well be that when using the exec() in a windows environment that redirection is to NUL:. /dev/null is a *nix null file.
I'm looking for the best, or any way really to start a process from php in the background so I can kill it later in the script.
Right now, I'm using: shell_exec($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'));