Hi!
Well, if this is the expected behavior, should not this mean that this
retry wrapper be in the next version of Durus? Convenience will save a
lot of stress.
-Ernie
On Fri, Aug 27, 2010 at 3:56 AM,
wrote:
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> Today's Topics:
>
> 1. Re: Persistent Session Management with Durus (Gabor Vitez)
> 2. Re: Persistent Session Management with Durus (Salman Haq)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Thu, 26 Aug 2010 20:01:39 +0200
> From: Gabor Vitez
> Subject: Re: [Quixote-users] Persistent Session Management with Durus
> To: Salman Haq
> Cc: quixote-users@mems-exchange.org
> Message-ID:
>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Hi!
>
> As far as I can tell, this is normal behaviour with Durus; I'd suggest
> wrapping every function that reads or writes durus with something like this:
>
> def writetransaction(func):
> """wrap writers with this"""
> def wrapper(*args, **kw):
> conn=dbconn.get_db()
> #bail after 1000 failures
> for dummy1 in xrange(1000):
> try:
> results=func(*args,**kw)
> conn.commit()
> return results
> except ConflictError:
> pass
> conn.abort()
> raise ConflictError
> return wrapper
>
> def readtransaction(func):
> """wrap readers with this"""
> def wrapper(*args, **kw):
> conn=dbconn.get_db()
> for dummy1 in xrange(1000):
> try:
> return func(*args,**kw)
> except ConflictError:
> pass
> conn.abort()
> raise ConflictError
> return wrapper
>
>
> dbconn is the global database connection object
>
> Best,
> G?bor
>
> On Thu, Aug 26, 2010 at 5:23 PM, Salman Haq wrote:
>
>> 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
>>
>>
>> _______________________________________________
>> Quixote-users mailing list
>> Quixote-users@mems-exchange.org
>> http://mail.mems-exchange.org/mailman/listinfo/quixote-users
>>
>>
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> ------------------------------
>
> Message: 2
> Date: Thu, 26 Aug 2010 14:42:46 -0400
> From: Salman Haq
> Subject: Re: [Quixote-users] Persistent Session Management with Durus
> To: quixote-users@mems-exchange.org
> Message-ID: <4C76B5A6.5070409@asti-usa.com>
> Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"
>
> Thanks Gabor! That works.
>
> Neither the Durus README file nor the online FAQs mention anything about
> re-try logic.
>
> Salman
>
> On 08/26/2010 02:01 PM, Gabor Vitez wrote:
>> Hi!
>>
>> As far as I can tell, this is normal behaviour with Durus; I'd suggest
>> wrapping every function that reads or writes durus with something like
>> this:
>>
>> def writetransaction(func):
>> """wrap writers with this"""
>> def wrapper(*args, **kw):
>> conn=dbconn.get_db()
>> #bail after 1000 failures
>> for dummy1 in xrange(1000):
>> try:
>> results=func(*args,**kw)
>> conn.commit()
>> return results
>> except ConflictError:
>> pass
>> conn.abort()
>> raise ConflictError
>> return wrapper
>>
>> def readtransaction(func):
>> """wrap readers with this"""
>> def wrapper(*args, **kw):
>> conn=dbconn.get_db()
>> for dummy1 in xrange(1000):
>> try:
>> return func(*args,**kw)
>> except ConflictError:
>> pass
>> conn.abort()
>> raise ConflictError
>> return wrapper
>>
>>
>> dbconn is the global database connection object
>>
>> Best,
>> G?bor
>>
>> On Thu, Aug 26, 2010 at 5:23 PM, Salman Haq > > wrote:
>>
>> 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
>>
>>
>> _______________________________________________
>> Quixote-users mailing list
>> Quixote-users@mems-exchange.org
>>
>> http://mail.mems-exchange.org/mailman/listinfo/quixote-users
>>
>>
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