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[Matthew Booth <mbooth@xxxxxxxxxx>]

Public bug reported:

I'm looking at conductor logs generated by a customer running RH OSP 10
(Newton). The logs appear to be corrupt in a manner I'd expect to see if
2 processes were writing to the same log file simultaneously. For
example:

===
2017-09-14 15:54:39.689 120626 ERROR nova.servicegroup.drivers.db     return self.dbapi.connect(*cargs, **cparams)
2017-09-14 15:54:39.689 120626 ERROR nova.s2017-09-14 15:54:39.690 120562 ERROR nova.servicegroup.drivers.db [-] Unexpected error while reporting service status
2017-09-14 15:54:39.690 120562 ERROR nova.servicegroup.drivers.db Traceback (most recent call last):
===

Notice how a new log starts part way through the second line above. This
also results in log entries in the wrong sort order:

===
2017-09-14 15:54:39.690 120562 ERROR nova.servicegroup.drivers.db     return self.dbapi.connect(*cargs, **cparams)
2017-09-14 15:54:39.690 120562 ERROR nova.servicegroup.drivers.db   File "/usr/lib/python2.7/site-packages/pymysql/__init__.py", line 88, in Connect
2017-09-14 15:54:39.689 120626 ERROR nova.servicegroup.drivers.db     return Connection(*args, **kwargs)
2017-09-14 15:54:39.689 120626 ERROR nova.servicegroup.drivers.db   File "/usr/lib/python2.7/site-packages/pymysql/connections.py", line 657, in __init__
===

Note how the first 2 lines are after the last 2 by timestamp, as
presumably the last 2 are a continuation of a previous log entry. This
confounds merge sorting of log files, which is exceptionally useful.

We also see truncated lines with no timestamp which aren't a
continuation of the previous line:

===
2017-09-14 15:54:39.690 120607 ERROR nova.servicegroup.drivers.db DBConnectionError: (pymysql.err.OperationalError) (2013, 'Lost connection to MySQL server during query') [SQL: u'SELECT 1']
2017-09-14 15:54:39.690 120607 ERROR nova.servicegroup.drivers.db 
elf._execute_and_instances(context)
===

I strongly suspect this is because multiple conductors are running in
separate processes, and are therefore not benefiting from the thread
safety of python's logging.

** Affects: nova
     Importance: Undecided
         Status: New

** Summary changed:

- Apparent lack of locking in logger
+ Apparent lack of locking in conductor logs

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https://bugs.launchpad.net/bugs/1718439

Title:
  Apparent lack of locking in conductor logs

Status in OpenStack Compute (nova):
  New

Bug description:
  I'm looking at conductor logs generated by a customer running RH OSP
  10 (Newton). The logs appear to be corrupt in a manner I'd expect to
  see if 2 processes were writing to the same log file simultaneously.
  For example:

  ===
  2017-09-14 15:54:39.689 120626 ERROR nova.servicegroup.drivers.db     return self.dbapi.connect(*cargs, **cparams)
  2017-09-14 15:54:39.689 120626 ERROR nova.s2017-09-14 15:54:39.690 120562 ERROR nova.servicegroup.drivers.db [-] Unexpected error while reporting service status
  2017-09-14 15:54:39.690 120562 ERROR nova.servicegroup.drivers.db Traceback (most recent call last):
  ===

  Notice how a new log starts part way through the second line above.
  This also results in log entries in the wrong sort order:

  ===
  2017-09-14 15:54:39.690 120562 ERROR nova.servicegroup.drivers.db     return self.dbapi.connect(*cargs, **cparams)
  2017-09-14 15:54:39.690 120562 ERROR nova.servicegroup.drivers.db   File "/usr/lib/python2.7/site-packages/pymysql/__init__.py", line 88, in Connect
  2017-09-14 15:54:39.689 120626 ERROR nova.servicegroup.drivers.db     return Connection(*args, **kwargs)
  2017-09-14 15:54:39.689 120626 ERROR nova.servicegroup.drivers.db   File "/usr/lib/python2.7/site-packages/pymysql/connections.py", line 657, in __init__
  ===

  Note how the first 2 lines are after the last 2 by timestamp, as
  presumably the last 2 are a continuation of a previous log entry. This
  confounds merge sorting of log files, which is exceptionally useful.

  We also see truncated lines with no timestamp which aren't a
  continuation of the previous line:

  ===
  2017-09-14 15:54:39.690 120607 ERROR nova.servicegroup.drivers.db DBConnectionError: (pymysql.err.OperationalError) (2013, 'Lost connection to MySQL server during query') [SQL: u'SELECT 1']
  2017-09-14 15:54:39.690 120607 ERROR nova.servicegroup.drivers.db 
  elf._execute_and_instances(context)
  ===

  I strongly suspect this is because multiple conductors are running in
  separate processes, and are therefore not benefiting from the thread
  safety of python's logging.

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