[Building Sakai] Fwd: Gradebook related production incident

[Kirschner, Beth]

If anyone who's recently worked in the Gradebook code has any suggestions on classes/methods to look at for this problem, please contact me or Zhen off-list. This seems like a risk for anyone that uses Gradebook in large classes. 

Thanks,
- Beth

Begin forwarded message:

> From: Zhen Qian <zqian at umich.edu>
> Subject: [Building Sakai] Gradebook related production incident
> Date: April 25, 2014 4:24:24 PM EDT
> To: sakai-dev <sakai-dev at collab.sakaiproject.org>
> 
> Hi, all:
> 
> We had a production issue with Gradebook usage recently, and filed SAK-26153 for it.
> 
> In summary, we had a large course site (1800 users) with many categorized Gradebook entries (70 GB items). Instructor sent out "grade available" announcement, and students all log in around the same time to check the final course grade. 
> 
> Upon every student login, the base GB query gets all students grade records for all GB items in site (count=100K). The problem is that there is NO caching implemented, so this query quickly ate up all available db connection pool and brought down app servers.
> 
> We are running a customized branch based on Gradebook 2.9.2. 
> 
> Has anyone seem similar problems in production? I looked at the latest trunk code for Gradebook, and did not find any recent caching fixes, either.
> 
> Thanks,
> 
> - Zhen
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