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[Mahara Bot <1514608@xxxxxxxxxxxxxxxxxx>]

Reviewed:  https://reviews.mahara.org/5774
Committed: https://git.mahara.org/mahara/mahara/commit/393fd87f5561a59b466468b303b0ee5587a9cef9
Submitter: Aaron Wells (aaronw@xxxxxxxxxxxxxxx)
Branch:    15.10_STABLE

commit 393fd87f5561a59b466468b303b0ee5587a9cef9
Author: Aaron Wells <aaronw@xxxxxxxxxxxxxxx>
Date:   Tue Nov 17 11:20:54 2015 +1300

Disable transactions in MySQL (Bug 1514608)

Mahara's usage of transactions has been causing
major deadlock issues in MySQL with InnoDB.
The immediate fix is to disable them.

behatnotneeded: Covered by existing tests

Change-Id: I2c7e6424e2d58502acd26fdd5d05c797e4ee5eac
(cherry picked from commit e52be8a3135c19b2ed306a5e16fdc0101d756f6d)

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https://bugs.launchpad.net/bugs/1514608

Title:
  MySQL deadlock issues with simultaneous users

Status in Mahara:
  Fix Committed
Status in Mahara 1.10 series:
  Fix Committed
Status in Mahara 15.04 series:
  In Progress
Status in Mahara 15.10 series:
  Fix Committed
Status in Mahara 16.04 series:
  Fix Committed

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://mahara.org/interaction/forum/topic.php?id=7309
  * https://mahara.org/interaction/forum/topic.php?id=7432

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