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POsubprocess blocks Django view
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4863405
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0
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3
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2011-02-01T13:53:56.503
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2011-06-26T09:31:53.180
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2017-05-23T12:01:22.063
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Body
I have a problem calling subprocess.Popen from a view: The view that calls subprocess.Popen is not displayed until the subprocess finishes. The server send "200 OK" immediately, but not the content of the page. My question is: Is this a limitation of Django's development server or am I doing it wrong? The server does not completely hangs, as other views can be processed in the meantime. There are already <a href="https://stackoverflow.com/search?q=Django+subprocess">a few questions on that topic</a> and Google gives <a href="http://www.google.com/#q=django+runserver+subprocess" rel="nofollow noreferrer">a few other threads</a>, but I cannot find a clear answer to my question. I believe this is not a python issue as this commands terminate immediately: <blockquote> python -c 'import subprocess; print subprocess.Popen(["/bin/sleep", "10"]).pid' </blockquote> <h2>How to reproduce</h2> <h3>Create test project & app:</h3> <blockquote> cd /tmp django-admin.py startproject django_test cd django_test ./manage.py startapp subprocess_test </blockquote> <h3>Replace urls.py & subprocess_test/views.py with:</h3> <ul> <li>urls.py: from django.conf.urls.defaults import * urlpatterns = patterns('',   (r'^hello$', 'subprocess_test.views.hello'),   (r'^start$', 'subprocess_test.views.start'), ) </li> <li>subprocess_test/views.py from django.http import HttpResponse import subprocess def hello(request):   return HttpResponse('Hello world!') def start(request):   subprocess.Popen(["/bin/sleep", "10"])   return HttpResponse('start done')</li> </ul> <h3>Test it:</h3> <blockquote> ./manage.py runserver 0.0.0.0:8000 </blockquote> Go to <a href="http://127.0.0.1:8000/hello" rel="nofollow noreferrer">http://127.0.0.1:8000/hello</a> and <a href="http://127.0.0.1:8000/start" rel="nofollow noreferrer">http://127.0.0.1:8000/start</a> <h2>Test result</h2> "start" takes 10s to load and "hello" can be loaded during that time. For example, I get such a log: <blockquote> [01/Feb/2011 07:20:57] "GET /hello HTTP/1.1" 200 12 [01/Feb/2011 07:21:01] "GET /start HTTP/1.1" 200 10 [01/Feb/2011 07:21:01] "GET /hello HTTP/1.1" 200 12 [01/Feb/2011 07:21:02] "GET /hello HTTP/1.1" 200 12 </blockquote> Using wget: <blockquote> wget <a href="http://127.0.0.1:8000/start" rel="nofollow noreferrer">http://127.0.0.1:8000/start</a> --2011-02-01 14:31:11-- <a href="http://127.0.0.1:8000/start" rel="nofollow noreferrer">http://127.0.0.1:8000/start</a> Connecting to 127.0.0.1:8000... connected. HTTP request sent, awaiting response... 200 OK Length: unspecified [text/html] Saving to: `start' <pre><code>[ <=> ] 10 --.-K/s in 9,5s </code></pre> 2011-02-01 14:31:21 (1,05 B/s) - « start » saved [10] </blockquote>
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<python><django><subprocess>
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subprocess blocks Django view
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