UsingWW: Sherman Wong - Viewing Problem with Library Browser

$inactiveTopic$ Viewing Problem with Library Browser

topic started 10/6/2004; 12:14:45 PM
last post 10/18/2004; 5:51:34 PM

$user$ Sherman Wong - Viewing Problem with Library Browser $blueArrow$
10/6/2004; 12:14:45 PM (reads: 2281, responses: 12)

There seems to be a problem with the Library Browser in WeBWorK 2.0.1 when viewing setDerivatives1 in the template directory. When I attempt to view these problems and I select more than 5 problems, I get essentially a blank screen. If I select 5, I can view the first 5 problems, but I can't view the next five or any subsequent problem. The Library Browser should have a way of allowing one to view the subsequent problems if, for some reason, it can't display a given problem.

The workaround that works is to select for "display mode" "None". This option permits one to "Try it" on the problems and to page to the next group of problems.

The problems that seem to be causing the viewing problem are nsc2s10p1.pg, nsc2s10p2.pg, and nsc2s10p3.pg. Oddly enough, there is no viewing problem when using an earlier version of WeBWorK.

Can you explain why these problems are stalling the Library Browser?

Thank you. Sherman

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$user$ Michael Gage - Re: Viewing Problem with Library Browser $blueArrow$
10/6/2004; 12:26:34 PM (reads: 2539, responses: 1)

I can't reproduce this using the Safari browser. I get the first 20 problems generated fairly quickly and a button at the bottom of the page which links to the next 20. You might try limiting the number of problems to 5 instead of 20. See if that helps. It might just be a matter of browser/computer speed.

The three problems you mention all have "on-the-fly" graphics -- perhaps something is making it hard for these graphics to be generated or to load into the browser.

Using alternate viewing modes, such as "none" or "jsMath" is also an option when you run into this kind of problem.

-- Mike

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$user$ John Jones - Re: Viewing Problem with Library Browser $blueArrow$
10/6/2004; 2:13:02 PM (reads: 2542, responses: 1)

For the three problems you mention, if you click on Try it, do the problems come up?

John

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$user$ Sherman Wong - Re: Viewing Problem with Library Browser $blueArrow$
10/6/2004; 2:39:01 PM (reads: 2845, responses: 0)

No, when I click on "Try it", nothing appears for any of the three problems. Because the graphics in the 3 problems are "on-the-fly", there must be "something" wrong with our configuration of version 2.0.1, since the graphics do appear on version 1.9 of WeBWorK.

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$user$ Sherman Wong - Re: Viewing Problem with Library Browser $blueArrow$
10/6/2004; 2:47:12 PM (reads: 2884, responses: 0)

I tried your suggestion to use jsMath, but to no avail. The only option that circumvents the difficulty in viewing the "on-the-fly" graphics for the 3 cited problems is "None".

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$user$ Michael Gage - Re: Viewing Problem with Library Browser $blueArrow$
10/6/2004; 3:29:33 PM (reads: 2527, responses: 0)

The most likely thing wrong with your setup is that the on-the-fly graphics are being created in one directory and your browser is looking for the images in another. This means adjusting some variables in global.conf so that they match up. You should also check the error log of the apache server, since that will give you any information if a graphic fails to be created, or if the browser tries to find the graphic in a different director from the one where it is being created.

Since the problem appears to be the "on the fly" graphics, rather than displaying equations, it makes sense that changing from "images" to "jsMath" won't change anything.

-- Mike

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$user$ Sherman Wong - Re: Viewing Problem with Library Browser $blueArrow$
10/7/2004; 7:51:23 AM (reads: 2533, responses: 0)

I relayed your suggestion to the fellow who works on seeing that the program performs as it ought to. He told me that the browser was looking at the correct file but that the file was of size 0 MB. This problem of the misdirection of the browser occurred before when we were testing WeBWorK 1.9.

Has there been any changes to the PG macro that handles such graphics?

Sherman

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$user$ Michael Gage - Re: Viewing Problem with Library Browser $blueArrow$
10/7/2004; 8:23:30 AM (reads: 2513, responses: 0)

If the contents of the file hasn't been created then there may messages in the error log. It could be a problem of getting GD to work properly, although if images mode for equations works then it is probably not GD, since that mode also uses GD to create the images. There haven't been any substantial changes made to these PG macros in some time.

You might want to remove the 0 MB file between tests since some caching is performed by WeBWorK and you want to make sure that it recreates the file. Pictures can be difficult to debug because the browsers also cache images -- use shift reload (refresh) often to insure that the browser is always getting the latest informationi.

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$user$ Sherman Wong - Re: Viewing Problem with Library Browser $blueArrow$
10/7/2004; 10:19:41 AM (reads: 2505, responses: 0)

Thank you for the suggestion about emptying the cache in the browser.

I'll pass on your other suggestion regarding the deletion of the 0 MB file.

Sherman

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$user$ Bjorn Nelson - Re: Viewing Problem with Library Browser $blueArrow$
10/8/2004; 10:20:21 AM (reads: 2489, responses: 0)

Hello, I work with Sherman. This actually relates to my post: http://webhost.math.rochester.edu/webworkdocs/discuss/msgReader$2832 [$graph->draw not drawing]

Unfortunately, my post got mangled but I don't think you need to parse it. From my debugging, I don't think it's a problem with insertGraph, but rather in the process of creating the $graph object. I am trying to follow it in the libraries.

Do you guys know of a way to debug web based perl? I know about perl -d, but I don't know of any tools for web based perl besides writing variables to a log file. I was looking at wwsh and I realize it's used to browse the classes. Can I use this to browse classes when they are used as an object? Is it just used to find the methods of classes?

Thanks, Bjorn

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$user$ Bjorn Nelson - Re: Viewing Problem with Library Browser $blueArrow$
10/8/2004; 10:29:57 AM (reads: 2511, responses: 0)

btw,

This is the version of gd and the gd module

gd-2.0.25,1 A graphics library for fast creation of images p5-GD-2.15 A perl5 interface to Gd Graphics Library version2

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$user$ Bjorn Nelson - Re: Viewing Problem with Library Browser $blueArrow$
10/8/2004; 1:26:40 PM (reads: 2514, responses: 1)

update,

I spoke with Mike and he suggested checking permissions and error logs. I had recursively given the "courses" directory ownership to the apache user account. Owner has full access to the directory.

I am getting an error: httpd in free(): error: modified (page-) pointer [Fri Oct 8 17:10:44 2004] [notice] child pid 52284 exit signal Abort trap (6)

I checked the resources for apache and it's given unlimited resources. The FreeBSD init (or rc) script for apache assigns it's resource profile to the www class. I defined this in the /etc/login.conf to point to default which in turn is set for unlimited resources.

apache version is 1.3.31 using webwork 2.0.1.

-Bjorn

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$user$ Bjorn Nelson - Re: Viewing Problem with Library Browser $blueArrow$
10/18/2004; 5:51:34 PM (reads: 2732, responses: 0)

What does the number in the cached images mean?

For instance, what does 463 come from: /usr/local/webwork2/courses/MTH9997/html/tmp/gif/professor-463-setFinal_Exam_Review_VIIprob1image1.png

compared to 64: /usr/local/webwork2/courses/MTH9997/html/tmp/gif/professor-64-setFinal_Exam_Review_VIIprob1image1.png

on another machine using the same PG. Why is it different? Are these just unique numbers?

-Bjorn

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Sherman Wong - Viewing Problem with Library Browser

Sherman Wong - Viewing Problem with Library Browser