title: wsgi django and random 500
body: <p>I have an application working on apache2. I wish to switch to uwsgi. 
  After deployment I have faced fancy problem with random errors like : </p>
  
  <pre><code>File "/usr/local/lib/python2.6/dist-packages/django/core/handlers/wsgi.py", line 272, in __call__
  30928-    response = self.get_response(request)
  30929-  File "/usr/local/lib/python2.6/dist-packages/django/core/handlers/base.py", line 169, in get_response
  30930-    response = self.handle_uncaught_exception(request, resolver, sys.exc_info())
  30931-  File "/usr/local/lib/python2.6/dist-packages/django/core/handlers/base.py", line 218, in handle_uncaught_exception
  30932-    return callback(request, **param_dict)
  30933-  File "/var/www/fancy_site/releases/current/fancy_site/utils/views.py", line 699, in server_error
  30934-    'GIGYA_API_KEY':settings.GIGYA_API_KEY,
  30935-  File "/usr/local/lib/python2.6/dist-packages/django/template/base.py", line 123, in render
  30936-    return self._render(context)
  30937-  File "/usr/local/lib/python2.6/dist-packages/django/test/utils.py", line 60, in instrumented_test_render
  30938-    return self.nodelist.render(context)
  30939-  File "/usr/local/lib/python2.6/dist-packages/django/template/base.py", line 744, in render
  30940-    bits.append(self.render_node(node, context))
  30941-  File "/usr/local/lib/python2.6/dist-packages/django/template/base.py", line 757, in render_node
  30942-    return node.render(context)
  30943-  File "/usr/local/lib/python2.6/dist-packages/django/template/loader_tags.py", line 105, in render
  30944-    compiled_parent = self.get_parent(context)
  30945-  File "/usr/local/lib/python2.6/dist-packages/django/template/loader_tags.py", line 102, in get_parent
  30946-    return get_template(parent)
  30947-  File "/usr/local/lib/python2.6/dist-packages/django/template/loader.py", line 157, in get_template
  30948-    template, origin = find_template(template_name)
  30949-  File "/usr/local/lib/python2.6/dist-packages/django/template/loader.py", line 134, in find_template
  30950-    source, display_name = loader(name, dirs)
  30951-  File "/usr/local/lib/python2.6/dist-packages/django/template/loader.py", line 42, in __call__
  30952-    return self.load_template(template_name, template_dirs)
  30953-  File "/usr/local/lib/python2.6/dist-packages/django/template/loader.py", line 48, in load_template
  30954-    template = get_template_from_string(source, origin, template_name)
  30955-  File "/usr/local/lib/python2.6/dist-packages/django/template/loader.py", line 168, in get_template_from_string
  30956-    return Template(source, origin, name)
  30957-  File "/usr/local/lib/python2.6/dist-packages/debug_toolbar/panels/template.py", line 37, in new_template_init
  30958-    old_template_init(self, template_string, origin, name)
  30959-  File "/usr/local/lib/python2.6/dist-packages/django/template/base.py", line 108, in __init__
  30960-    self.nodelist = compile_string(template_string, origin)
  30961-  File "/usr/local/lib/python2.6/dist-packages/django/template/base.py", line 136, in compile_string
  30962-    return parser.parse()
  30963-  File "/usr/local/lib/python2.6/dist-packages/django/template/base.py", line 239, in parse
  30964-    compiled_result = compile_func(self, token)
  30965-  File "/usr/local/lib/python2.6/dist-packages/django/template/defaulttags.py", line 1054, in load
  30966-    (taglib, e))
  30967-django.template.base.TemplateSyntaxError: 'sso_token' is not a valid tag library: Template library sso_token not found, tried django.templatetags.sso_token,django.contrib.admin.templatetags.sso_token,django.contrib.webdesign.templatetags.sso_token,paging.templatetags.sso_token,sentry.templatetags.sso_token,tinymce.templatetags.sso_token,pagination.templatetags.sso_token,rosetta.templatetags.sso_token,flatblocks.templatetags.sso_token,oembed.templatetags.sso_token,debug_toolbar.templatetags.sso_token,memcache_status.templatetags.sso_token,mailchimp.templatetags.sso_token
  </code></pre>
  
  <p>django send me similar exceptions on mail like :  no module name views - which is ofcourse not true, because this application works on apache since two years : )</p>
  
  <p>I have no idea where the problem is - I know I am not able to reproduce it at my stage env - which is a clone production machine. As far as I know it's not a code depend error or application problem. </p>
  
  <p>at procution I am using current configuration:</p>
  
  <p>I am using :
  django 1.3.1
  uWSGI 1.1
  nginx 1.0.12-1~dotdeb.0
  python 2.6
  debian 6.0.3
  2 x QC Xeon E5540 with 8 gb ram</p>
  
  <p>those machines are under physicall load balancer supported by hosting company.</p>
  
  <p>nginx cfg  :</p>
  
  <pre><code>server { 
    listen 80;
          server_name www.fancy_site.fancy_domain fancy_site.fancy_domain
          server_name_in_redirect off;
          access_log /path/to/file.log;
  
          if ($host = 'fancy_site' ) {
              rewrite ^/(.*)$ http://www.fancy_site.fancy_domain/$1 permanent;
          }
  
          location /media/ {
              alias /path/to/media/;
              expires max;
          }
  
          location  /site_media/ {
              alias /path/to/media/;
              expires max;
          }
  
          location /static/ {
              alias   /path/to/static/;
              expires max;
          }
  
          gzip  on;
          gzip_http_version 1.0;
          gzip_vary on;
          gzip_comp_level 3;
          gzip_proxied any;
          gzip_types text/plain text/css application/json application/x-javascript text/xml application/xml application/xml+rss text/javascript;
          gzip_buffers 16 8k;
          gzip_disable “MSIE [1-6].(?!.*SV1)”;
  
          location / {
              uwsgi_pass unix://path/to/uwsgi.socket;
              include uwsgi_params;
          }
  
  }
  </code></pre>
  
  <p>uWSGI cfg : </p>
  
  <pre><code>prefix = /path/to/prod_direcotry
  master = true
  processes = 80
  uid = fancy_application
  gid = www-data
  memory-report = true
  max-requests = 800
  stdout_logfile = /path/to/uwsgi.log
  daemonize = /path/to/uwsgi.log
  redirect_stderr = true
  logfile-chown=www-data
  socket = /path/to/uwsgi.socket
  chdir = /path/to/application_direcotry
  pythonpath = /path/to/to_current_release_of_application
  env = DJANGO_SETTINGS_MODULE=application_direcotry.settings
  module = django.core.handlers.wsgi:WSGIHandler()
  touch-reload = %(prefix)/touch_to_restart
  </code></pre>
  
  <p>I'd like to ask You community if someone had the same or similar problem. Maybe someone solved and wish to share with how ? </p>
  
  <p>regards
  Lukasz</p>