Re: problems running subprocess inside django view
On Sat, Jan 28, 2012 at 12:05 AM, Mark Lancaster wrote: > I'm having problems running subprocess inside a django view using: > > result = subprocess.Popen([ , ], > stdout=subprocess.PIPE).communicate()[0] > > exactly the same method works perfectly inside a regular python > script. > > Should I be using a different method to initiate a script? You shouldn't be trying to initiate a script from within a view. The request-response cycle needs to be short lived. The responsiveness of the user's experience is directly tied to how long it takes for your server to complete executing a view; if you're invoking subprocesses (especially long lived subprocesses) as part of a view, then you aren't going to b "Oh, but my subprocess *will* be short lived!" you say? Well, you've still got a problem -- because your user can hit cancel at any time during a request, closing a connection, which can cause all sorts of interesting problems with managing dangling subprocesses. If you need to execute something long lived, you should break it down into parts: 1) A view that creates a "job". This doesn't need to be any more than writing a single entry in a database table. 2) A view that can be used to poll the status of the job. 3) A background task -- completely outside the request-response cycle -- that executes jobs, and reports the status back to the database table. This ensures that the expensive process is handled out of the request-response cycle, yielding a more responsive interface, and giving you better scalability, too (since your ability to handle background processes is decoupled from your ability to handle user requests for background processes). There are many ways to achieve the background task -- celery is one popular option, but you can organise an quick and nasty proof-of-concept using cron. Yours, Russ Magee %-) -- You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-users@googlegroups.com. To unsubscribe from this group, send email to django-users+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/django-users?hl=en.
Re: problems running subprocess inside django view
As the same user? Are you running with manage.py runserver? Generally it is a bad idea to call subprocess from a web process context. A blocking call you don't expect might time out the client and/or hang your server. Check out Django-celery. Create a tasks.py and have your view call a task. Sent from my iPhone On Jan 28, 2012, at 6:41 AM, Eugene Gavrish wrote: > You are not alone with this problem. But I haven't got any decision. > Maybe its django-specific with Popen?? > > I divided my task in two part: first cron-driven disk file generation. > Second - from django-view this file parsing. > It satisfied my goals, but question with Popen is still opened... > > > On 27 янв, 20:05, Mark Lancaster wrote: >> I'm having problems running subprocess inside a django view using: >> >> result = subprocess.Popen([ , ], >> stdout=subprocess.PIPE).communicate()[0] >> >> exactly the same method works perfectly inside a regular python >> script. >> >> Should I be using a different method to initiate a script? >> >> Thanks > > -- > You received this message because you are subscribed to the Google Groups > "Django users" group. > To post to this group, send email to django-users@googlegroups.com. > To unsubscribe from this group, send email to > django-users+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/django-users?hl=en. > -- You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-users@googlegroups.com. To unsubscribe from this group, send email to django-users+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/django-users?hl=en.
Re: problems running subprocess inside django view
You are not alone with this problem. But I haven't got any decision. Maybe its django-specific with Popen?? I divided my task in two part: first cron-driven disk file generation. Second - from django-view this file parsing. It satisfied my goals, but question with Popen is still opened... On 27 янв, 20:05, Mark Lancaster wrote: > I'm having problems running subprocess inside a django view using: > > result = subprocess.Popen([ , ], > stdout=subprocess.PIPE).communicate()[0] > > exactly the same method works perfectly inside a regular python > script. > > Should I be using a different method to initiate a script? > > Thanks -- You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-users@googlegroups.com. To unsubscribe from this group, send email to django-users+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/django-users?hl=en.
problems running subprocess inside django view
I'm having problems running subprocess inside a django view using: result = subprocess.Popen([ , ], stdout=subprocess.PIPE).communicate()[0] exactly the same method works perfectly inside a regular python script. Should I be using a different method to initiate a script? Thanks -- You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-users@googlegroups.com. To unsubscribe from this group, send email to django-users+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/django-users?hl=en.
