Re: Persistent Session Management with Durus
Salman Haq <[email protected]> Thu, 26 Aug 2010 11:23:08 -0400
| Newsgroups | gmane.comp.web.quixote.user |
|---|---|
| Message-ID | <[email protected]> |
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Some new info included at the end:
On 08/26/2010 10:49 AM, Salman Haq wrote:
> |Hi,
>
> I'm developing an application using Quixote 2.6 and following the example in altdemo.py pretty closely for persistent session management with Durus.
> The application is serving static files very unreliably. One in five requests for a static file receive a HTTP 500 response code. Eg: if an html page embeds 50
> script or img tags, requests for about 10 of them will fail. For each of these failed requests, the following traceback is received:
>
> Traceback (most recent call last):
> || File "/usr/lib/python2.4/site-packages/quixote2/publish.py", line 275, in process_request
> || output = self.try_publish(request)
> || File "/usr/lib/python2.4/site-packages/quixote2/publish.py", line 255, in try_publish
> || self.finish_successful_request()
> || File "/usr/lib/python2.4/site-packages/quixote2/publish.py", line 138, in finish_successful_request||
> || self.session_manager.finish_successful_request()
> || File "/usr/lib/python2.4/site-packages/quixote2/session.py", line 388, in finish_successful_request||
> || self.commit_changes(session)
> || File "/usr/lib/python2.4/site-packages/ACE_rms/auth/session.py", line 44, in commit_changes
> || self.durus_connection.commit()
> || File "/usr/lib/python2.4/site-packages/durus/connection.py", line 254, in commit
> || assert not self.invalid_oids, "still conflicted: missing abort()"
> ||AssertionError: still conflicted: missing abort()
>
> My application is running as a SCGI process behind Apache. Static files are served by Quixote via the StaticDirectory class and not by Apache.
> The Durus server runs as a stand-alone process on localhost:2951 and a connection object to it is created as follows:
>
> def publisher_factory ():
> """ returns a quixote2 Publisher instance that publishes
> the RootDirectory with persistent session management support.
> """
> conn = Connection(ClientStorage("127.0.0.1", 2951))
> session_manager = DurusSessionManager(conn)
> return Publisher(RootDirectory(), session_manager=session_manager, display_exceptions='plain')
>
>
> The application sub-classes SessionManager and Session exactly as described in the snippet below:
>
> ----
>
> from quixote2.session import Session, SessionManager
> from durus.persistent import Persistent
> from durus.persistent_dict import PersistentDict
>
> class PersistentSession (Session, Persistent):
> """ Persistent version of default quixote Session class.
> This class can be overridden if desired.
> """
> pass
>
> class DurusSessionManager (SessionManager):
> """ Loads/stores quixote sessions from/to a Durus db.
> Overrides forget_changes() and commit_changes() as described in quixote
> docs and altdemo.py.
> """
>
> def __init__ (self, durus_connection, session_class=PersistentSession):
> """ Load sessions from the durus db and init the SessionManager.
> (inst, class) : inst
> durus_connection: a Connection object to a Durus db.
> session_class: session class to use (must override PeristentSession).
> """
> self.durus_connection = durus_connection
> root = self.durus_connection.get_root()
> sessions = root.get('auth.sessions', None)
>
> if not sessions:
> sessions = PersistentDict()
> root['auth.sessions'] = sessions
> self.durus_connection.commit()
>
> SessionManager.__init__(self,
> session_class=session_class,
> session_mapping=sessions)
>
> def forget_changes (self, session):
> self.durus_connection.abort()
>
> def commit_changes (self, session):
> self.durus_connection.commit()
>
> -----
>
> Can anyone tell me why my Durus database thinks it's in a conflicted state?
>
> Thank you,
> Salman
> |||
Requests for static files are not the only ones that are likely to fail.
AJAX requests also tend to cause HTTP 500. Again, the failures are
unpredictable,
but usually one in a group of three or four simultaneous AJAX requests
by the browser can fail.
And the AssertionError mentioned above is not the only error raised by
the application. I have noticed a WriteConflictError too, albeit less
frequently:
Traceback (most recent call last):
File "/usr/lib/python2.4/site-packages/quixote2/publish.py", line 275, in process_request
output = self.try_publish(request)
File "/usr/lib/python2.4/site-packages/quixote2/publish.py", line 255, in try_publish
self.finish_successful_request()
File "/usr/lib/python2.4/site-packages/quixote2/publish.py", line 138, in finish_successful_request
self.session_manager.finish_successful_request()
File "/usr/lib/python2.4/site-packages/quixote2/session.py", line 388, in finish_successful_request
self.commit_changes(session)
File "/usr/lib/python2.4/site-packages/ACE_rms/auth/session.py", line 45, in commit_changes
self.durus_connection.commit()
File "/usr/lib/python2.4/site-packages/durus/connection.py", line 273, in commit
self.storage.end(self._handle_invalidations)
File "/usr/lib/python2.4/site-packages/durus/client_storage.py", line 82, in end
handle_invalidations(oid_list)
File "/usr/lib/python2.4/site-packages/durus/connection.py", line 303, in _handle_invalidations
raise WriteConflictError(conflicts)
WriteConflictError: oids=[2]
I'm still learning Durus, but I suspect quite a few people on this list
are familiar with its internals.
Thanks,
Salman
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Some new info included at the end:<br>
<br>
<br>
On 08/26/2010 10:49 AM, Salman Haq wrote:
<blockquote cite="mid:[email protected]" type="cite">
<meta http-equiv="content-type"
content="text/html; charset=ISO-8859-1">
<pre role="list"><code class="wrappedText focusRow" role="listitem">Hi,
I'm developing an application using Quixote 2.6 and following the example in altdemo.py pretty closely for persistent session management with Durus.
The application is serving static files very unreliably. One in five requests for a static file receive a HTTP 500 response code. Eg: if an html page embeds 50
script or img tags, requests for about 10 of them will fail. For each of these failed requests, the following traceback is received:
Traceback (most recent call last):
</code><code class="wrappedText focusRow" role="listitem"> File "/usr/lib/python2.4/site-packages/quixote2/publish.py", line 275, in process_request
</code><code class="wrappedText focusRow" role="listitem"> output = self.try_publish(request)
</code><code class="wrappedText focusRow" role="listitem"> File "/usr/lib/python2.4/site-packages/quixote2/publish.py", line 255, in try_publish
</code><code class="wrappedText focusRow" role="listitem"> self.finish_successful_request()
</code><code class="wrappedText focusRow" role="listitem"> File "/usr/lib/python2.4/site-packages/quixote2/publish.py", line 138, in finish_successful_request</code><code
class="wrappedText focusRow" role="listitem">
</code><code class="wrappedText focusRow" role="listitem"> self.session_manager.finish_successful_request()
</code><code class="wrappedText focusRow" role="listitem"> File "/usr/lib/python2.4/site-packages/quixote2/session.py", line 388, in finish_successful_request</code><code
class="wrappedText focusRow" role="listitem">
</code><code class="wrappedText focusRow" role="listitem"> self.commit_changes(session)
</code><code class="wrappedText focusRow" role="listitem"> File "/usr/lib/python2.4/site-packages/ACE_rms/auth/session.py", line 44, in commit_changes
</code><code class="wrappedText focusRow" role="listitem"> self.durus_connection.commit()
</code><code class="wrappedText focusRow" role="listitem"> File "/usr/lib/python2.4/site-packages/durus/connection.py", line 254, in commit
</code><code class="wrappedText focusRow" role="listitem"> assert not self.invalid_oids, "still conflicted: missing abort()"
</code><code class="wrappedText focusRow" role="listitem">AssertionError: still conflicted: missing abort()
My application is running as a SCGI process behind Apache. Static files are served by Quixote via the StaticDirectory class and not by Apache.
The Durus server runs as a stand-alone process on localhost:2951 and a connection object to it is created as follows:
def publisher_factory ():
""" returns a quixote2 Publisher instance that publishes
the RootDirectory with persistent session management support.
"""
conn = Connection(ClientStorage("127.0.0.1", 2951))
session_manager = DurusSessionManager(conn)
return Publisher(RootDirectory(), session_manager=session_manager, display_exceptions='plain')
The application sub-classes SessionManager and Session exactly as described in the snippet below:
----
from quixote2.session import Session, SessionManager
from durus.persistent import Persistent
from durus.persistent_dict import PersistentDict
class PersistentSession (Session, Persistent):
""" Persistent version of default quixote Session class.
This class can be overridden if desired.
"""
pass
class DurusSessionManager (SessionManager):
""" Loads/stores quixote sessions from/to a Durus db.
Overrides forget_changes() and commit_changes() as described in quixote
docs and altdemo.py.
"""
def __init__ (self, durus_connection, session_class=PersistentSession):
""" Load sessions from the durus db and init the SessionManager.
(inst, class) : inst
durus_connection: a Connection object to a Durus db.
session_class: session class to use (must override PeristentSession).
"""
self.durus_connection = durus_connection
root = self.durus_connection.get_root()
sessions = root.get('auth.sessions', None)
if not sessions:
sessions = PersistentDict()
root['auth.sessions'] = sessions
self.durus_connection.commit()
SessionManager.__init__(self,
session_class=session_class,
session_mapping=sessions)
def forget_changes (self, session):
self.durus_connection.abort()
def commit_changes (self, session):
self.durus_connection.commit()
-----
Can anyone tell me why my Durus database thinks it's in a conflicted state?
Thank you,
Salman
</code><code class="wrappedText focusRow" role="listitem"></code></pre>
</blockquote>
<br>
Requests for static files are not the only ones that are likely to
fail. AJAX requests also tend to cause HTTP 500. Again, the failures
are unpredictable,<br>
but usually one in a group of three or four simultaneous AJAX requests
by the browser can fail. <br>
<br>
And the AssertionError mentioned above is not the only error raised by
the application. I have noticed a WriteConflictError too, albeit less
frequently:<br>
<pre>Traceback (most recent call last):</pre>
<pre> File "/usr/lib/python2.4/site-packages/quixote2/publish.py", line 275, in process_request
output = self.try_publish(request)
File "/usr/lib/python2.4/site-packages/quixote2/publish.py", line 255, in try_publish
self.finish_successful_request()
File "/usr/lib/python2.4/site-packages/quixote2/publish.py", line 138, in finish_successful_request
self.session_manager.finish_successful_request()
File "/usr/lib/python2.4/site-packages/quixote2/session.py", line 388, in finish_successful_request
self.commit_changes(session)
File "/usr/lib/python2.4/site-packages/ACE_rms/auth/session.py", line 45, in commit_changes
self.durus_connection.commit()
File "/usr/lib/python2.4/site-packages/durus/connection.py", line 273, in commit
self.storage.end(self._handle_invalidations)
File "/usr/lib/python2.4/site-packages/durus/client_storage.py", line 82, in end
handle_invalidations(oid_list)
File "/usr/lib/python2.4/site-packages/durus/connection.py", line 303, in _handle_invalidations
raise WriteConflictError(conflicts)
WriteConflictError: oids=[2]</pre>
I'm still learning Durus, but I suspect quite a few people on this list
are familiar with its internals.<br>
<br>
Thanks,<br>
Salman<br>
<br>
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