Run php script as daemon process

Question

I need to run a php script as daemon process  wait for instructions and do stuff   cron job will not do it for me because actions need to be taken as soon as instruction arrives  I know PHP is not really the best option for daemon processes due to memory management issues  but due to various reasons I have to use PHP in this case  I came across a tool by libslack called Daemon  http   libslack org daemon  it seems to help me manage daemon processes  but there hasn t been any updates in the last 5 years  so I wonder if you know some other alternatives suitable for my case  Any information will be really appreciated

User · Answer

I wrote and deployed a simple php-daemon, code is online here

https://github.com/jmullee/PhpUnixDaemon

Features: privilege dropping, signal handling, logging

I used it in a queue-handler (use case: trigger a lengthy operation from a web page, without making the page-generating php wait, i.e. launch an asynchronous operation) https://github.com/jmullee/PhpIPCMessageQueue

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I recently had a need for a cross-platform solution  Windows  Mac  and Linux  to the problem of running PHP scripts as daemons   I solved the problem by writing my own C   based solution and making binaries   https   github com cubiclesoft service-manager   Full support for Linux  via sysvinit   but also Windows NT services and Mac OSX launchd   If you just need Linux  then a couple of the other solutions presented here work well enough and  depending on the flavor   There is also Upstart and systemd these days  which have fallbacks to sysvinit scripts   But half of the point of using PHP is that it is cross-platform in nature  so code written in the language has a pretty good chance of working everywhere as-is   Deficiencies start showing up when certain external native OS-level aspects enter the picture such as system services  but you ll get that problem with most scripting languages   Attempting to catch signals as someone here suggested in PHP userland is not a good idea   Read the documentation on pcntl signal   carefully and you will quickly learn that PHP handles signals using some rather unpleasant methods  specifically   ticks   that chew up a bunch of cycles for something rarely seen by processes  i e  signals    Signal handling in PHP is also only barely available on POSIX platforms and support differs based on the version of PHP   It initially sounds like a decent solution but it falls pretty short of being truly useful   PHP has also been getting better about memory leak issues as time progresses   You still have to be careful  the DOM XML parser tends to leak still  but I rarely see runaway processes these days and the PHP bug tracker is pretty quiet by comparison to the days of yore

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There is more than one way to solve this problem   I do not know the specifics but perhaps there is another way to trigger the PHP process   For instance if you need the code to run based on events in a SQL database you could setup a trigger to execute your script    This is really easy to do under PostgreSQL  http   www postgresql org docs current static external-pl html    Honestly I think your best bet is to create a Damon process using nohup   nohup allows the command to continue to execute even after the user has logged out   nohup php myscript php  amp    There is however a very serious problem    As you said PHP s memory manager is complete garbage   it was built with the assumption that a script is only executing for a few seconds and then exists    Your PHP script will start to use GIGABYTES of memory after only a few days   You MUST ALSO create a cron script that runs every 12 or maybe 24 hours that kills and re-spawns your php script like this   killall -3 php nohup php myscript php  amp    But what if the script was in the middle of a job   Well kill -3 is an interrupt  its the same as doing a ctrl c  on the CLI    Your php script can catch this interrupt and exit gracefully using the PHP pcntl library  http   php oregonstate edu manual en function pcntl-signal php  Here is an example   function clean up       GLOBAL  lock    mysql close      fclose  lock    exit      pcntl signal SIGINT   clean up      The idea behind the  lock is that the PHP script can open a file with a fopen  file   w      Only one process can have a write lock on a file   so using this you can make sure that only one copy of your PHP script is running    Good Luck

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I run a large number of PHP daemons     I agree with you that PHP is not the best  or even a good  language for doing this  but the daemons share code with the web-facing components so overall it is a good solution for us   We use daemontools for this   It is smart  clean and reliable   In fact we use it for running all of our daemons   You can check this out at http   cr yp to daemontools html   EDIT  A quick list of features    Automatically starts the daemon on reboot Automatically restart dameon on failure Logging is handled for you  including rollover and pruning Management interface   svc  and  svstat  UNIX friendly  not a plus for everyone perhaps

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You could start your php script from the command line  i e  bash  by using     nohup php myscript php  amp     the  amp  puts your process in the background   Edit  Yes  there are some drawbacks  but not possible to control  That s just wrong  A simple kill processid will stop it  And it s still the best and simplest solution

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You can   Use nohup as Henrik suggested  Use screen and run your PHP program as a regular process inside that  This gives you more control than using nohup   Use a daemoniser like http   supervisord org   it s written in Python but can daemonise any command line program and give you a remote control to manage it    Write your own daemonise wrapper like Emil suggested but it s overkill IMO    I d recommend the simplest method  screen in my opinion  and then if you want more features or functionality  move to more complex methods

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you can check pm2 here is  http   pm2 keymetrics io   create a ssh file  such as worker sh put into your php script that you will deal with   worker sh  php  path myscript php   daemon start  pm2 start worker sh   Cheers  that is it

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Check out https   github com shaneharter PHP-Daemon  This is an object-oriented daemon library  It has built-in support for things like logging and error recovery  and it has support for creating background workers

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Extending Emil Ivaov answer  You can do the following to close STDIN  STDOUT AND STDERROR in php  if   fclose STDIN         exit  Could not close STDIN       if   fclose STDOUT         exit  Could not close STDOUT       if   fclose STDERR         exit  Could not close STDERR        STDIN   fopen   dev null    r     STDOUT   fopen   dev null    w     STDERR   fopen   var log our error log    wb      Basically you close the standard streams so that PHP has no place to write  The following fopen calls will set the standard IO to  dev null   I have read this from book of Rob Aley - PHP beyond the web

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I was looking for a simple solution without having to install additional stuff and compatible with common hostings that allow SSH access  I ve ended up with this setup for my chat server  -rwxr-xr-x  1 crazypoems psacln   309 ene 30 14 01 checkChatServerRunning sh -rw-r--r--  1 crazypoems psacln  3018 ene 30 13 12 class chathandler php -rw-r--r--  1 crazypoems psacln    29 ene 30 14 05 cron log -rw-r--r--  1 crazypoems psacln  2560 ene 29 08 04 index php -rw-r--r--  1 crazypoems psacln  2672 ene 30 13 29 php-socket php -rwxr-xr-x  1 crazypoems psacln   310 ene 30 14 04 restartChatServer sh -rwxr-xr-x  1 crazypoems psacln   122 ene 30 13 28 startChatServer sh -rwxr-xr-x  1 crazypoems psacln   224 ene 30 13 56 stopChatServer sh  And the scripts  startChatServer sh    bin bash nohup  opt plesk php 5 6 bin php -q  var www vhosts crazypoems org httpdocs chat php-socket php  gt   dev null  amp   stopChatServer sh    bin bash PID  ps -eaf   grep   var www vhosts crazypoems org httpdocs chat php-socket php    grep -v grep   awk   print  2    if     quot  quot       quot  PID quot      then   echo  quot killing  PID quot    kill -9  PID else   echo  quot not running quot  fi  restartChatServer sh    bin bash PID  ps -eaf   grep   var www vhosts crazypoems org httpdocs chat php-socket php    grep -v grep   awk   print  2    if     quot  quot       quot  PID quot      then   echo  quot killing  PID quot    kill -9  PID else   echo  quot not running quot  fi echo  quot Starting again quot   var www vhosts crazypoems org httpdocs chat startChatServer sh  And last but not least  I have put this last script on a cron job  to check if the  quot chat server is running quot   and if not  to start it  Cron job every minute -bash-4 1  crontab -l                                    var www vhosts crazypoems org httpdocs chat checkChatServerRunning sh  gt   var www vhosts crazypoems org httpdocs chat cron log  checkChatServerRunning sh    bin bash PID  ps -eaf   grep   var www vhosts crazypoems org httpdocs chat php-socket php    grep -v grep   awk   print  2    if     quot  quot       quot  PID quot      then   echo  quot Chat server running on  PID quot  else   echo  quot Not running  going to start it quot     var www vhosts crazypoems org httpdocs chat startChatServer sh fi  So with this setup   I manually can control the service with the scripts when needed  eg  maintenance  The cron job will start the server on reboot  or on crash

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With new  systemd you can create a service   You must create a file or a symlink in   etc systemd system   eg  myphpdaemon service and place content like this one  myphpdaemon will be the name of the service    Unit  Description My PHP Daemon Service  May your script needs MySQL or other services to run  eg  MySQL Memcached Requires mysqld service memcached service  After mysqld service memcached service   Service  User root Type simple TimeoutSec 0 PIDFile  var run myphpdaemon pid ExecStart  usr bin php -f  srv www myphpdaemon php arg1 arg2 gt   dev null 2 gt  dev null  ExecStop  bin kill -HUP  MAINPID  It s the default you can change whats happens on stop command  ExecReload  bin kill -HUP  MAINPID KillMode process  Restart on-failure RestartSec 42s  StandardOutput null  If you don t want to make toms of logs you can set it null if you sent a file or some other options it will send all php output to this one  StandardError  var log myphpdaemon log  Install  WantedBy default target   You will be able to start  get status  restart and stop  the services using the command   systemctl  lt start status restart stop enable gt  myphpdaemon   The PHP script should have a kind of  loop  to continue running    lt  php gc enable      while   connection aborted      PHP SAPI     cli          Code Logic      sleep and usleep could be useful     if  PHP SAPI     cli             if  rand 5  100    5    0                gc collect cycles      Forces collection of any existing garbage cycles                     Working example    Unit  Description PHP APP Sync Service Requires mysqld service memcached service After mysqld service memcached service   Service  User root Type simple TimeoutSec 0 PIDFile  var run php app sync pid ExecStart  bin sh -c   usr bin php -f  var www app private server cron app sync php  2 gt  amp 1  gt   var log app sync log  KillMode mixed  Restart on-failure RestartSec 42s   Install  WantedBy default target   If your PHP routine should be executed once in a cycle  like a diggest   you may should use a shell or bash script to be invoked into systemd service file instead of PHP directly  for example      usr bin env bash script path   app services    while       do      clear     php -f   script path   1   php  fixedparameter   2    gt   dev null 2 gt  dev null     sleep 1 done   If you chose these option you should change the KillMode to mixed to processes  bash main  and PHP child  be killed   ExecStart  app phpservice runner sh phpfile parameter   gt   dev null 2 gt  dev null KillMode process   This method also is effective if you re facing a memory leak      Note  Every time that you change your  myphpdaemon service  you must   run  systemctl daemon-reload   but do worry if you not do  it will be   alerted when is needed

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If you can - grab a copy of Advanced Programming in the UNIX Environment  The entire chapter 13 is devoted to daemon programming  Examples are in C  but all the function you need have wrappers in PHP  basically the pcntl and posix extensions    In a few words - writing a daemon  this is posible only on  nix based OS-es - Windows uses services  is like this    Call umask 0  to prevent permission issues  fork   and have the parent exit  Call setsid    Setup signal processing of SIGHUP  usually this is ignored or used to signal the daemon to reload its configuration  and SIGTERM  to tell the process to exit gracefully   fork   again and have the parent exit  Change the current working dir with chdir    fclose   stdin  stdout and stderr and don t write to them  The corrrect way is to redirect those to either  dev null or a file  but I couldn t find a way to do it in PHP  It is possible when you launch the daemon to redirect them using the shell  you ll have to find out yourself how to do that  I don t know     Do your work    Also  since you are using PHP  be careful for cyclic references  since the PHP garbage collector  prior to PHP 5 3  has no way of collecting those references and the process will memory leak  until it eventually crashes

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Another option is to use Upstart  It was originally developed for Ubuntu  and comes packaged with it by default   but is intended to be suitable for all Linux distros   This approach is similar to Supervisord and daemontools  in that it automatically starts the daemon on system boot and respawns on script completion   How to set it up   Create a new script file at  etc init myphpworker conf  Here is an example     Info description  My PHP Worker  author       Jonathan     Events start on startup stop on shutdown    Automatically respawn respawn respawn limit 20 5    Run the script    Note  in this example  if your PHP script returns   the string  ERROR   the daemon will stop itself  script         exec  usr bin php -f  path to your script php     ERROR     amp  amp    stop  exit 1    end script   Starting  amp  stopping your daemon   sudo service myphpworker start sudo service myphpworker stop   Check if your daemon is running   sudo service myphpworker status   Thanks  A big thanks to Kevin van Zonneveld  where I learned this technique from

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As others have already mentioned  running PHP as a daemon is quite easy  and can be done using a single line of command  But the actual problem is keeping it running and managing it  I ve had the same problem quite some time ago and although there are plenty of solutions already available  most of them have lots of dependencies or are difficult to use and not suitable for basic usages  I wrote a shell script that can manage a any process application including PHP cli scripts  It can be set as a cronjob to start the application and will contain the application and manage it  If it s executed again  for example via the same cronjob  it check if the app is running or not  if it does then simply exits and let its previous instance continue managing the application   I uploaded it to github  feel free to use it   https   github com sinasalek EasyDeamonizer  EasyDeamonizer  Simply watches over your application  start  restart  log  monitor  etc   a generic script to make sure that your appliation remains running properly  Intentionally it uses process name instread of pid lock file to prevent all its side effects and keep the script as simple and as stirghforward as possible  so it always works even when EasyDaemonizer itself is restarted  Features   Starts the application and optionally a customized delay for each start Makes sure that only one instance is running Monitors CPU usage and restarts the app automatically when it reaches the defined threshold Setting EasyDeamonizer to run via cron to run it again if it s halted for any reason Logs its activity

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Kevin van Zonneveld wrote a very nice detailed article on this  in his example he makes use of the System Daemon PEAR package  last release date on 2009-09-02

[php] Run php script as daemon process

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