Page tree
Skip to end of metadata
Go to start of metadata


Yardstick logging design


By default:

  • DEBUG messages are logged into the log file
  • INFO messages are logging to stderr




Loggers are based on yardstick module heirarchy. The base logger is named 'yardstick', sub loggers are called 'yardstick.benchmarks.contexts.heat'. This is achevied by using LOG = logging.getLogger(__name__) where __name__ is the name of the module, e.g. yardstick.benchmarks.contexts.heat.

The file and stream handlers are added to the root logger, logging.root, also known as logging.getLogger('')

logging.getLogger('') is logging.root


https://docs.python.org/2/howto/logging.html#logging-flow

 

yardstick logging flow

 

Logger.propagate

If this evaluates to true, events logged to this logger will be passed to the handlers of higher level (ancestor) loggers, in addition to any handlers attached to this logger. Messages are passed directly to the ancestor loggers’ handlers - neither the level nor filters of the ancestor loggers in question are considered.

If this evaluates to false, logging messages are not passed to the handlers of ancestor loggers.

The constructor sets this attribute to True.

 

If you attach a handler to a logger and one or more of its ancestors, it may emit the same record multiple times. In general, you should not need to attach a handler to more than one logger - if you just attach it to the appropriate logger which is highest in the logger hierarchy, then it will see all events logged by all descendant loggers, provided that their propagate setting is left set to True. A common scenario is to attach handlers only to the root logger, and to let propagation take care of the rest.

 

 

Logger.setLevel(lvl)

Sets the threshold for this logger to lvl. Logging messages which are less severe than lvl will be ignored. When a logger is created, the level is set to NOTSET (which causes all messages to be processed when the logger is the root logger, or delegation to the parent when the logger is a non-root logger). Note that the root logger is created with level WARNING.

The term ‘delegation to the parent’ means that if a logger has a level of NOTSET, its chain of ancestor loggers is traversed until either an ancestor with a level other than NOTSET is found, or the root is reached.

If an ancestor is found with a level other than NOTSET, then that ancestor’s level is treated as the effective level of the logger where the ancestor search began, and is used to determine how a logging event is handled.

If the root is reached, and it has a level of NOTSET, then all messages will be processed. Otherwise, the root’s level will be used as the effective level.

See Logging Levels for a list of levels.

 

 

  • No labels