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[Zhenyu Zheng <zhengzhenyu@xxxxxxxxxx>]

Public bug reported:

Currently, when querying user quota usages, the query process is not
Order Preserved, this may causes deadlock in bulk creations. That is,
for example, there are 2 rows in the DB, the first call get the record
from the 1st row and lock, at the same time, an another call get the
record from the 2nd row and lock, then both calls will wait for the
other call to release the row and will cause the deadlock scenario.

Simply add order_by(id) to the query can avoid the deadlock by calls
that are not order preserved.

** Affects: nova
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1485408

Title:
  Deadlock when querying user quota usage.

Status in OpenStack Compute (nova):
  New

Bug description:
  Currently, when querying user quota usages, the query process is not
  Order Preserved, this may causes deadlock in bulk creations. That is,
  for example, there are 2 rows in the DB, the first call get the record
  from the 1st row and lock, at the same time, an another call get the
  record from the 2nd row and lock, then both calls will wait for the
  other call to release the row and will cause the deadlock scenario.

  Simply add order_by(id) to the query can avoid the deadlock by calls
  that are not order preserved.

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