# Forking behaves differently when using apache **URL:** \ **Category:** Ruby\ **Created:** [November 12, 2009, 12:37am UTC](https://www.ruby-forum.com/t/forking-behaves-differently-when-using-apache/178841 "2009-11-12T00:37:56Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![nicken](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/d07c76/32.png) [@nicken](https://www.ruby-forum.com/u/nicken)\ **Post date:** [November 12, 2009, 12:37am UTC](https://www.ruby-forum.com/t/forking-behaves-differently-when-using-apache/178841/1 "2009-11-12T00:37:56Z")
I want a CGI script to fire off another process and continue executing (or even terminate) without waiting for the process to finish. I wrote this: #!/usr/bin/ruby require ‘cgi’ c = CGI.new fork do sleep 5 end c.out {“hello!\n”} When I execute that from the command line, it IMMEDIATELY prints “Content-Type…hello!” and exits. When I run it on Apache and access it from my browser, on the other hand, it PAUSES for five seconds, THEN displays “hello!”. What’s going on? Why does it behave differently with Apache? I am using Apache/2.2.12 (Ubuntu) with ruby 1.8.7 (2009-06-12 patchlevel 174) [x86\_64-linux]. Thanks in advance… ---
**Author:** ![nicken](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/d07c76/32.png) [@nicken](https://www.ruby-forum.com/u/nicken)\ **Post date:** [November 12, 2009, 12:45am UTC](https://www.ruby-forum.com/t/forking-behaves-differently-when-using-apache/178841/2 "2009-11-12T00:45:23Z")
On 11 Nov 2009, at 23:37, Nick B. wrote: > When I execute that from the command line, it IMMEDIATELY prints > > Thanks in advance… Do you have Apache configured to use preforked workers or to use threads? Ellie ## Eleanor McHugh Games With Brains [http://slides.games-with-brains.net](http://slides.games-with-brains.net) raise ArgumentError unless @reality.responds\_to? :reason ---
**Author:** ![nicken](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/d07c76/32.png) [@nicken](https://www.ruby-forum.com/u/nicken)\ **Post date:** [November 12, 2009, 9:28am UTC](https://www.ruby-forum.com/t/forking-behaves-differently-when-using-apache/178841/3 "2009-11-12T09:28:00Z")
2009/11/12 Nick B. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid): > When I execute that from the command line, it IMMEDIATELY prints > “Content-Type…hello!” and exits. When I run it on Apache and access it > from my browser, on the other hand, it PAUSES for five seconds, THEN > displays “hello!”. > > What’s going on? Why does it behave differently with Apache? All sorts of possible reasons: Apache might buffer your output and maybe it even waits for the child to return. What happens if you do this: #!/usr/bin/ruby require ‘cgi’ c = CGI.new fork do $stdin.close $stdout.close $stderr.close sleep 5 end c.out {“hello!\n”} Cheers robert ---
**Author:** ![nicken](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/d07c76/32.png) [@nicken](https://www.ruby-forum.com/u/nicken)\ **Post date:** [November 12, 2009, 5:13pm UTC](https://www.ruby-forum.com/t/forking-behaves-differently-when-using-apache/178841/4 "2009-11-12T17:13:24Z")
2009/11/12 Nick B. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid): > Elanor: I’m using the default apache2 config as distributed by Ubuntu > 9.10. Is there a particular Apache directive I could use to make it > behave the way I expect? > > Robert: Closing STDIN and STDOUT seemed to do the trick! Thanks. Just so > I grok this: Apache, by default, will wait until all subprocesses close > their IO streams before it sends a CGI program’s output to the browser? It seems so. You’ll probably have more luck with this question when placed in an Apache forum. Reading the docs might also help. 😉 > Is that correct? Is there a better way to kick off such processes? Or is > manually closing STDIN and STDOUT every time I fork the ideal solution? Since I have no idea what your process does or is supposed to do I cannot really tell. You’ll probably want to look into the features available to daemonize a process, e.g [http://www.ruby-doc.org/core-1.9/classes/Process.html#M002265](http://www.ruby-doc.org/core-1.9/classes/Process.html#M002265) Kind regards robert ---
**Author:** ![nicken](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/d07c76/32.png) [@nicken](https://www.ruby-forum.com/u/nicken)\ **Post date:** [November 13, 2009, 12:31am UTC](https://www.ruby-forum.com/t/forking-behaves-differently-when-using-apache/178841/5 "2009-11-13T00:31:52Z")
On 12 Nov 2009, at 15:10, Nick B. wrote: > Elanor: I’m using the default apache2 config as distributed by Ubuntu > 9.10. Is there a particular Apache directive I could use to make it > behave the way I expect? On reflection I suspect it wouldn’t make a lot of difference as… > Robert: Closing STDIN and STDOUT seemed to do the trick! Thanks. > Just so > I grok this: Apache, by default, will wait until all subprocesses > close > their IO streams before it sends a CGI program’s output to the > browser? > Is that correct? Is there a better way to kick off such processes? > Or is > manually closing STDIN and STDOUT every time I fork the ideal > solution? …it appears that when Apache launches a CGI process it waits for that process to close the std[in|out] file descriptors before sending the page to the browser, so closing them is clearly the way to go if using direct forking. However there are alternative options you could explore such as using a message queue (BackgroundDRb, unix message queues, etc.) or named pipe to communicate with a process (or processes) created outside the context of Apache. Ellie ## Eleanor McHugh Games With Brains [http://slides.games-with-brains.net](http://slides.games-with-brains.net) raise ArgumentError unless @reality.responds\_to? :reason ---
**Author:** ![nicken](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/d07c76/32.png) [@nicken](https://www.ruby-forum.com/u/nicken)\ **Post date:** [November 12, 2009, 4:10pm UTC](https://www.ruby-forum.com/t/forking-behaves-differently-when-using-apache/178841/6 "2009-11-12T16:10:42Z")
Elanor: I’m using the default apache2 config as distributed by Ubuntu 9.10. Is there a particular Apache directive I could use to make it behave the way I expect? Robert: Closing STDIN and STDOUT seemed to do the trick! Thanks. Just so I grok this: Apache, by default, will wait until all subprocesses close their IO streams before it sends a CGI program’s output to the browser? Is that correct? Is there a better way to kick off such processes? Or is manually closing STDIN and STDOUT every time I fork the ideal solution?