[LON-CAPA-admin] Action locked

[Stuart Raeburn]

Locking functionality was added in 2.7 to discourage users from  
changing roles or logging out when either of the following two actions  
are in progress:

(a) Publishing a directory in Construction Space
(b) Grading a bubble sheet exam.

Under the current implementation when a lock needs to be set in (a) or  
(b), a session.lock.id item is appended to the user's environment  
(where id is a unique lock ID), and a call is registered with the  
request object's clean-up handler to delete the lock when the request  
has been handled.

If the publication process has ended, and the "Action locked" message  
is displayed that suggests that the clean-up handler was either not  
called, or the corresponding lock was not cleanly removed from the  
user's environment. I'll take a look at this and see if there  
conditions under which the lock might persist even if the publication  
process completed.

The Apache response 409 code (an error code) is generated by LON-CAPA  
when displaying either the roles screen or the logout screen, in a  
case where one or more locks are still set in a user's environment.  
LON-CAPA's Apache configuration causes the web server to call  
/adm/preferences?action=lockwarning whenever either roles or logout  
return a 409 response code.  This is the screen which provides the  
user with the ability to override the "Action locked" state and delete  
a lock which is impeding a role change or logout.

Stuart Raeburn
MSU LON-CAPA group

Quoting Todd Ruskell <truskell at mines.edu>:

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> I've been seeing this on occasion too, running 2.7.1.  I've so far only
> encountered it when having multiple tabs open to the same server--I'll
> publish a resource in one tab, and, for example, as CC in another tab
> I'll try to view the new resource, and occasionally get "Action locked"
> even though according to the tab in which I'm publishing, the publish is
> finished and I have already gone on to other things.
>
> I just figured my use of multiple tabs somehow confused lon-capa on
> occasion.
>
> Todd
>
> Stefan Bisitz wrote:
>> Hi Hong-Kie,
>>
>> Are you sure? If this was a bug, then it's likely an Apache bug.
>> LON-CAPA redirects the 409 Apache error page to the "Action locked"
>> page. This leads to the questions
>>
>> a) Why did the server encounter the 409 error?
>> Or
>> b) Is there a way to confirm that the 409 error really occurred?
>>
>> Stefan Bisitz
>>
>>
>>
>> Am Freitag, den 13.02.2009, 09:50 -0500 schrieb H.K. Ng:
>>> Hi Stefan, I think this is a bug. I have also noticed this. Do you
>>> want to file a bug report? - hk
>>>
>>> At 09:29 AM 2/13/2009, you wrote:
>>>> Hi,
>>>>
>>>> An Author wanted to logout some minutes ago but got the error message
>>>> "Action locked". The screen says that the publication of a directory is
>>>> still in progress.
>>>>
>>>> It is indeed true, that this directory has been published. This has been
>>>> done 1.5 hours before the logout try. The author said that no error
>>>> messages or other issues occurred during the publication. After that
>>>> nothing special happened.
>>>>
>>>> As found about the related error code 409, we checked the httpd
>>>> error_log file. There aren't many entries for today and those don't look
>>>> like related to the locking issue.
>>>>
>>>> This is the first time ever that is error was encountered. We are afraid
>>>> to corrupt the resource space, if we click the "override" button. The
>>>> session is still active. Any ideas where to look or what to do?
>>>>
>>>> Thanks in advance,
>>>> Stefan Bisitz
>>>>
>>>>
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