# Background processes in post-receive hook 5 messages from 2011-04-02 to 2011-04-03. Participants: James Pickens, Junio C Hamano, Sitaram Chamarty, Joe Ratterman, Jonathan Nieder. Thread: https://gitlist.dev/t/26969 ## James Pickens, 2011-04-02 23:03 Subject: Background processes in post-receive hook Message-ID: URL: https://gitlist.dev/e/AANLkTinrEt6DkwhknpDZ0iV9PR%2B7bBd3DAaPRJOgNFTG%40mail.gmail.com ``` Hi, I have a post-receive hook (bash script) that launches several background processes and exits immediately. I do that so I don't have to wait for the background processes to finish every time I push to the repository, but Git seems to wait for them to finish anyways, even though the post-receive hook itself already exited. Is there any way to stop Git from waiting and let the push finish immediately? Sorry if I'm missing something obvious... Thanks, James ``` ## Junio C Hamano, 2011-04-03 00:35 Subject: Re: Background processes in post-receive hook Message-ID: <7v8vvsgoj8.fsf@alter.siamese.dyndns.org> URL: https://gitlist.dev/e/7v8vvsgoj8.fsf%40alter.siamese.dyndns.org In-Reply-To: ``` James Pickens writes: > I have a post-receive hook (bash script) that launches several background > processes and exits immediately. I do that so I don't have to wait for the > background processes to finish every time I push to the repository, but Git > seems to wait for them to finish anyways, even though the post-receive hook > itself already exited. Is there any way to stop Git from waiting and let the > push finish immediately? An easy way to do that is to run whatever lengthy process you do not want to wait for using echo "that command" | at now in the hook ;-). ``` ## Sitaram Chamarty, 2011-04-03 03:22 Subject: Re: Background processes in post-receive hook Message-ID: URL: https://gitlist.dev/e/BANLkTin4-fMhi_5H1oZ%2BgPB99stj5GRjVA%40mail.gmail.com In-Reply-To: ``` On Sun, Apr 3, 2011 at 4:33 AM, James Pickens wrote: > Hi, > > I have a post-receive hook (bash script) that launches several background > processes and exits immediately.  I do that so I don't have to wait for the > background processes to finish every time I push to the repository, but Git > seems to wait for them to finish anyways, even though the post-receive hook > itself already exited.  Is there any way to stop Git from waiting and let the > push finish immediately?  Sorry if I'm missing something obvious... interestingly, the double fork trick doesn't work either... ( ( long-running-command & ) ) What Junio said may be the only alternative... ``` ## Joe Ratterman, 2011-04-03 04:59 Subject: Re: Background processes in post-receive hook Message-ID: URL: https://gitlist.dev/e/AANLkTim3Eu%2BrHc3_7_PWsALK3QwuzyX2Anbn8o6aCbAE%40mail.gmail.com In-Reply-To: ``` On Sat, Apr 2, 2011 at 10:22 PM, Sitaram Chamarty wrote: > interestingly, the double fork trick doesn't work either... > >  ( ( long-running-command & ) ) I think that is because the hook is still reading from the command's stdout. If you close stdout/stderr, I would expect it to work. For example, the "sort" command below cannot exit until all sub-programs have finished feeding it data. You can see that despite the levels of forking involved, the stdout of perl and the stdin of sort are the same. $ ( ( perl -e 'sleep 60; print "THERE\n";' & ) ) | sort > /tmp/out & [1] 4033 $ ps h ... 4033 pts/10 S 0:00 sort 4035 pts/10 S 0:00 perl -e sleep 60; print "THERE\n"; ... $ ll /proc/{4035,4033}/fd /proc/4033/fd: total 0 lr-x------ 1 jratt bgq 64 Apr 2 23:49 0 -> pipe:[55227211] l-wx------ 1 jratt bgq 64 Apr 2 23:49 1 -> /tmp/out lrwx------ 1 jratt bgq 64 Apr 2 23:49 2 -> /dev/pts/10 /proc/4035/fd: total 0 lr-x------ 1 jratt bgq 64 Apr 2 23:49 0 -> /dev/null l-wx------ 1 jratt bgq 64 Apr 2 23:49 1 -> pipe:[55227211] lrwx------ 1 jratt bgq 64 Apr 2 23:49 2 -> /dev/pts/10 $ cat /tmp/out $ fg ( ( perl -e 'sleep 60; print "THERE\n";' & ) ) | sort > /tmp/out $ cat /tmp/out THERE However, this version exits before the shell returns to the prompt (and the output is lost). $ ( ( perl -e 'close STDOUT; close STDERR;sleep 60; print "THERE\n";' & ) ) | sort > /tmp/out & [1] 4097 [1]+ Done ( ( perl -e 'close STDOUT; close STDERR;sleep 60; print "THERE\n";' & ) ) | sort > /tmp/out $ Joe ``` ## Jonathan Nieder, 2011-04-03 05:06 Subject: Re: Background processes in post-receive hook Message-ID: <20110403050619.GA32750@elie> URL: https://gitlist.dev/e/20110403050619.GA32750%40elie In-Reply-To: ``` Sitaram Chamarty wrote: > interestingly, the double fork trick doesn't work either... > > ( ( long-running-command & ) ) Hopefully closing the output pipe does the trick. exec long-running-command >&- 2>&- & Thanks for an interesting example. Jonathan ```