I have a MAAS with 100+ nodes in it, and in its maas-django.log I'm seeing these errors from time to time, especially if I try to start many nodes at once.
ERROR 2014-12-12 16:30:25,747 maasserver ################################ Exception: deadlock detected
DETAIL: Process 746 waits for ShareLock on transaction 43344353; blocked by process 742.
Process 742 waits for ExclusiveLock on tuple (5,3) of relation 16585 of database 16385; blocked by process 746.
HINT: See server log for query details.
################################
ERROR 2014-12-12 16:30:25,747 maasserver Traceback (most recent call last):
File "/usr/lib/python2.7/dist-packages/django/core/handlers/base.py", line 112, in get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/usr/lib/python2.7/dist-packages/maasserver/api/pxeconfig.py", line 171, in pxeconfig
node.save()
File "/usr/lib/python2.7/dist-packages/maasserver/models/cleansave.py", line 38, in save
return super(CleanSave, self).save(*args, **kwargs)
File "/usr/lib/python2.7/dist-packages/maasserver/models/timestampedmodel.py", line 55, in save
return super(TimestampedModel, self).save(*args, **kwargs)
File "/usr/lib/python2.7/dist-packages/django/db/models/base.py", line 545, in save
force_update=force_update, update_fields=update_fields)
File "/usr/lib/python2.7/dist-packages/django/db/models/base.py", line 573, in save_base
updated = self._save_table(raw, cls, force_insert, force_update, using, update_fields)
File "/usr/lib/python2.7/dist-packages/django/db/models/base.py", line 635, in _save_table
forced_update)
File "/usr/lib/python2.7/dist-packages/django/db/models/base.py", line 679, in _do_update
return filtered._update(values) > 0
File "/usr/lib/python2.7/dist-packages/django/db/models/query.py", line 507, in _update
return query.get_compiler(self.db).execute_sql(None)
File "/usr/lib/python2.7/dist-packages/django/db/models/sql/compiler.py", line 975, in execute_sql
cursor = super(SQLUpdateCompiler, self).execute_sql(result_type)
File "/usr/lib/python2.7/dist-packages/django/db/models/sql/compiler.py", line 781, in execute_sql
cursor.execute(sql, params)
File "/usr/lib/python2.7/dist-packages/django/db/backends/util.py", line 53, in execute
return self.cursor.execute(sql, params)
File "/usr/lib/python2.7/dist-packages/django/db/utils.py", line 99, in __exit__
six.reraise(dj_exc_type, dj_exc_value, traceback)
File "/usr/lib/python2.7/dist-packages/django/db/backends/util.py", line 53, in execute
return self.cursor.execute(sql, params)
OperationalError: deadlock detected
DETAIL: Process 746 waits for ShareLock on transaction 43344353; blocked by process 742.
Process 742 waits for ExclusiveLock on tuple (5,3) of relation 16585 of database 16385; blocked by process 746.
HINT: See server log for query details.
This bug has been reported and fixed on upstream MAAS. However, provided that the bug was listed on the debian changelog, this appears as needing verification for pending SRU [1]. This bug did not affect current MAAS in Ubuntu, hence setting this to verification-done to unblock pending SRU.
[1]:http://