** Using WeBWorK **

Short Description: When I create a hardcopy PDF of multiple homework sets the system does not release the memory.


I are currently preparing to upgrade to WeBWork 2.7 . For our installation we have about 6000 students per semester. Our test server is currently running with 4 cpu cores and 24GB of RAM.

To install WeBWork I used the LIVE CD to install the system. I followed the directions found here http://webwork.maa.org/wiki/Installing_from_WW2.7_Ubuntu12.04_Vanilla_LiveDVD#.Upzd5HmA1aQ

Once that was completed and everything was double checked I followed this guide’s Optional Configurations section. http://webwork.maa.org/wiki/Installation_Manual_for_2.7_on_Ubuntu_12.04#Optional_Configurations_2 Currently I have only completed Option A (wwtmp) and Option B (lighttpd).

Once the installation was completed and tested successfully I then unarchived an archived class from our live installation. At this point everything seems to be working great.

Once I log in as the administrator I select the Classlist Editor2 and select a test student that I have created. Once I click on the students name I scroll down to the bottom of the screen and select “Download PDF or TeX Hardcopy for selected sets”. Then on the right hand side I select all of the homework sets. There are about 30 homework sets. At the bottom I select “Student Answers”, “Correct Answers”, “Hints” and “Solutions”. I then select “Generate hardcopy for selected sets and selected users”. At this point the system takes about 30 seconds to generate the PDF. At this time, the memory usage goes up about 2GB and eventually creates a 1MB PDF.

Even after waiting over an hour the system has yet to release the memory. In previous tests, I repeated the PDF generation test multiple times eventually using all 24 GB of RAM and the system still did not release any of the memory. If I only select a single Homework set the memory usage is significantly smaller but it never decreases. In our previous installation ( 2.4 ) the memory would spike but would be released a few minutes later and go back to normal.

I am concerned that 6000 students may generate enough PDF’s to run the system out of memory.

Please let me know if there is any other information I can provide.

Thanks in advance.
Steve