Reverted #8688 for now, since it merely introduced different bugs, rather than

fixing the problem. We have a plan B (and plan C, if needed), so this will be
fixed in a different way.

Refs #8616.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@8707 bcc190cf-cafb-0310-a4f2-bffc1f526a37

AUTHORS

@@ -363,7 +363,6 @@ answer newbie questions, and generally made Django that much better:
     Ben Slavin <benjamin.slavin@gmail.com>
     sloonz <simon.lipp@insa-lyon.fr>
     SmileyChris <smileychris@gmail.com>
-    Warren Smith <warren@wandrsmith.net>
     smurf@smurf.noris.de
     Vsevolod Solovyov
     sopel

django/contrib/sessions/backends/file.py

@@ -5,9 +5,7 @@ import tempfile
 from django.conf import settings
 from django.contrib.sessions.backends.base import SessionBase, CreateError
 from django.core.exceptions import SuspiciousOperation, ImproperlyConfigured
-from django.core.files import locks
 
-IO_LOCK_SUFFIX = "_iolock"
 
 class SessionStore(SessionBase):
     """
@@ -44,35 +42,17 @@ class SessionStore(SessionBase):
 
         return os.path.join(self.storage_path, self.file_prefix + session_key)
 
-    def _key_to_io_lock_file(self, session_key=None):
-        """
-        Get the I/O lock file associated with this session key.
-        """
-        return self._key_to_file(session_key) + IO_LOCK_SUFFIX
-
     def load(self):
         session_data = {}
         try:
-            # Open and acquire a shared lock on the I/O lock file before
-            # attempting to read the session file.  This makes us wait to read
-            # the session file until another thread or process is finished
-            # writing it.
-            lock_path = self._key_to_io_lock_file()
-            io_lock_file = open(lock_path, "rb")
-            locks.lock(io_lock_file, locks.LOCK_SH)
+            session_file = open(self._key_to_file(), "rb")
             try:
-                session_file = open(self._key_to_file(), "rb")
                 try:
-                    try:
-                        session_data = self.decode(session_file.read())
-                    except (EOFError, SuspiciousOperation):
-                        self.create()
-                finally:
-                    session_file.close()
+                    session_data = self.decode(session_file.read())
+                except (EOFError, SuspiciousOperation):
+                    self.create()
             finally:
-                locks.unlock(io_lock_file)
-                io_lock_file.close()
-                os.unlink(lock_path)
+                session_file.close()
         except IOError:
             pass
         return session_data
@@ -96,23 +76,11 @@ class SessionStore(SessionBase):
         # truncating the file to save.
         session_data = self._get_session(no_load=must_create)
         try:
-            # Open and acquire an exclusive lock on the I/O lock file before
-            # attempting to write the session file.  This makes other threads
-            # or processes wait to read or write the session file until we are
-            # finished writing it.
-            lock_path = self._key_to_io_lock_file()
-            io_lock_file = open(lock_path, "wb")
-            locks.lock(io_lock_file, locks.LOCK_EX)
+            fd = os.open(self._key_to_file(self.session_key), flags)
             try:
-                fd = os.open(self._key_to_file(self.session_key), flags)
-                try:
-                    os.write(fd, self.encode(session_data))
-                finally:
-                    os.close(fd)
+                os.write(fd, self.encode(session_data))
             finally:
-                locks.unlock(io_lock_file)
-                io_lock_file.close()
-                os.unlink(lock_path)
+                os.close(fd)
         except OSError, e:
             if must_create and e.errno == errno.EEXIST:
                 raise CreateError