Forum archive 2000-2006

Dana P Williams - Missing problems

Dana P Williams - Missing problems

by Arnold Pizer -
Number of replies: 0
inactiveTopicMissing problems topic started 11/9/2004; 8:09:56 AM
last post 11/11/2004; 2:36:48 PM
userDana P Williams - Missing problems  blueArrow
11/9/2004; 8:09:56 AM (reads: 1647, responses: 9)
In our assignment for today, one student (at least) has only 5 problems instead of the 9 most students have (and are supposed to have). I am at a loss to explain and/or fix it. Here is the errow message that appears when I use the "home sets editor" to look at his problems.

Any suggestions?

Thanks, Dana


 Problems for set 8Nov04

The set 8Nov04 is assigned to all users .
Editing user-specific overrides for Farmer
WeBWorK error

An error occured while processing your request. For help, please send mail to this site's
webmaster ( giving as much information as you can
about the error and the date and time that the error occured.

Warning messages

Error messages

problem 6 for set 8Nov04 and user Farmer not found.
at /var/webwork2/lib/WeBWorK/ContentGenerator/Instructor/ line 422.

<| Post or View Comments |>

userGavin LaRose - Re: Missing problems  blueArrow
11/9/2004; 8:29:45 AM (reads: 1862, responses: 0)
Hi Dana,

The only time I've seen this type of error in a class with a large number (more than 700) of students in a class when running WeBWorK 1.x. In that case the set assignment (that is, set building) operation timed out, with the result that some of the students didn't get all sets assigned to them. As a work-around I didn't try and assign all of the sets at once and that resolved the problem. I don't think I've ever seen a case where part of a set got assigned to a student, however.


<| Post or View Comments |>

userDana P Williams - Re: Missing problems  blueArrow
11/9/2004; 8:36:31 AM (reads: 1840, responses: 0)
Gavin reminds me that I should have provided more information in my first posting. The class is somewhat large: about 235. (Thankfully, much smaller than the 700 Gavin had.) Although I have successfully built many assignments for this class, this one did fail for some 15 students and I had to re-assign it. No doubt there is glich in the database somewhere as a result. My problem now is to deal with what I hope is this one student.

Thanks, Dan

<| Post or View Comments |>

userMichael Gage - Re: Missing problems  blueArrow
11/9/2004; 10:27:58 AM (reads: 1836, responses: 0)

If I remember correctly you are using sql databases. This means that you can use something like myphpAdmin to delete the problem_user entry for this student.

It would be wise to back up the database first of course.

I haven't had direct experience with this problem. To the extent we can, we try to build in tests that maintain the database integrity but there is always more to do. It's also a tricky balance between warning one of problems and failing gracefully enough to allow a fix.

To address the immediate problem: myPHPAdmin is one potential solution. Using webwork/bin/wwsh to directly manipulate the database might be another, but I'll need to let Sam Hathaway take the lead in explaining that.

Keep us informed of how this problem is resolved. I'm sure that it will be useful in other cases.

Take care,


<| Post or View Comments |>

userRobert (Rochester ugrad) - Re: Missing problems  blueArrow
11/9/2004; 11:05:05 AM (reads: 1824, responses: 0)
I can't tell you what went wrong but if you go to the Set Assigner page, you can unassign the set for that one student and then assign it to him again (if there are more studenst you can do them all at once too). If the student has already started working on the set, anything he has done will be lost but if that's the case you can always just manually give him credit for the ones he had gotten right (you'd have to look at his score first and write it down somewhere before you unassign the set).

<| Post or View Comments |>

userSam Hathaway - Re: Missing problems  blueArrow
11/9/2004; 11:05:06 AM (reads: 1851, responses: 0)
A simple solution might be to unassign set 8Nov04 from user Farmer and then reassign it. You can do this by clicking on the number of users to whom the set is assigned in the Hmwk Set List. If it works, that student will lose their attempt data, etc.

If that doesn't work, you can do it manually using phpMyAdmin or the command-line mysql client (if you're comfortable with that). First, back up the database using mysqldump. Delete the records from set_user and problem_user for that user and set:

DELETE FROM set_user WHERE user_id='Farmer' and set_id='8Nov04';
DELETE FROM problem_user WHERE user_id='Farmer' and set_id='8Nov04';

As for bin/wwsh, you can use it to monkey with the database using the API defined in lib/WeBWorK/ However, the assignment routines are not part of that module and are not accessible without bringing up the full WeBWorK environment. (Note to self: these could be moved to a Utils module.)

<| Post or View Comments |>

userDana P Williams - Re: Missing problems  blueArrow
11/9/2004; 3:11:22 PM (reads: 1876, responses: 0)
I would like to thank everyone for their helpful suggestions. I had wanted to avoid unassigning the set if possible, but the situation resolved itself. When we showed the problem to our system administrator, the computer, no doubt out of fear for a higher intellect, simply showed him all nine problems. The system administrator said it had something to do with restarting apache, but as I had dropped to the floor in supplication, I am not sure. I will ask him to post a more technical description.

<| Post or View Comments |>

userarūnas Burdulis - Re: Missing problems  blueArrow
11/11/2004; 10:49:38 AM (reads: 1799, responses: 0)
The problem has most likely litte to do with WW2. Logs show that at the moment the problem set assignment loop was running, apache received a SIGHUP and the MySQL connections quit. I don't have a record for why did Apache had to be stopped on that day. There was one issue with apache at approximately that time, when apache process was pegged at 60--70% CPU time for already an hour or so while there seemed to be no WW activity.

<| Post or View Comments |>

userJohn Jones - Re: Missing problems  blueArrow
11/11/2004; 12:23:10 PM (reads: 1793, responses: 0)
High apache activity for a long time with little webwork activity can be a sign of a problem with an infinite loop in it. I think the most recent versions of webwork files catch this, but maybe it isn't in your version of webwork, or maybe there is a scenario where it doesn't get caught.


<| Post or View Comments |>

userarūnas Burdulis - Re: Missing problems  blueArrow
11/11/2004; 2:36:48 PM (reads: 1789, responses: 0)
We run WW2 from CVS, rel-2-0-patches, as of July 25.


<| Post or View Comments |>