MySQL deadlock issues with simultaneous users
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
Mahara |
Fix Released
|
High
|
Aaron Wells | ||
1.10 |
Fix Released
|
High
|
Aaron Wells | ||
15.04 |
Fix Released
|
High
|
Aaron Wells | ||
15.10 |
Fix Released
|
High
|
Aaron Wells |
Bug Description
The patch in Bug 1492919 resolved the deadlock issues for some users, but others are still reporting that they are getting deadlocks. This seems to be an issue unique to MySQL, and it can happen with as few as 2 or 3 concurrent users.
It has been reported across all stable versions. Strangely, it seems to be a relatively recent issue (i.e. we never heard this with Mahara 1.8 or 1.7, etc), so this suggests it was triggered by something that changed fairly recently. One possible candidate is our switch to the mysqli driver (before that Mahara wasn't doing transactions at all, in mysql).
See also:
* https:/
* https:/
Changed in mahara: | |
milestone: | none → 15.04.5 |
description: | updated |
description: | updated |
no longer affects: | mahara/16.04 |
Changed in mahara: | |
status: | Fix Committed → Fix Released |
Most of our reports are for sites on 15.04, and it seems to get worse when there are more users. It's possible this was some sort of underlying deadlock potential in Mahara that was made worse by some low-level code change in 15.04, like something that gets triggered by init.php or some other frequent bit of code, which was not triggered as frequently before.