patroni.log module

Patroni logging facilities.

Daemon processes will use a 2-step logging handler. Whenever a log message is issued it is initially enqueued in-memory and is later asynchronously flushed by a thread to the final destination.

class patroni.log.PatroniLogger

Bases: threading.Thread

Logging thread for the Patroni daemon process.

It is a 2-step logging approach. Any time a log message is issued it is initially enqueued in-memory, and then asynchronously flushed to the final destination by the logging thread.

See also

QueueHandler: object used for enqueueing messages in-memory.

Variables:
  • DEFAULT_LEVEL – default logging level (INFO).
  • DEFAULT_TRACEBACK_LEVEL – default traceback logging level (ERROR).
  • DEFAULT_FORMAT – default format of log messages (%(asctime)s %(levelname)s: %(message)s).
  • NORMAL_LOG_QUEUE_SIZE – expected number of log messages per HA loop when operating under a normal situation.
  • DEFAULT_MAX_QUEUE_SIZE – default maximum queue size for holding a backlog of log messages that are pending to be flushed.
  • LOGGING_BROKEN_EXIT_CODE – exit code to be used if it detects(5).
  • log_handler – log handler that is currently being used by the thread.
  • log_handler_lock – lock used to modify log_handler.
DEFAULT_FORMAT = '%(asctime)s %(levelname)s: %(message)s'
DEFAULT_LEVEL = 'INFO'
DEFAULT_MAX_QUEUE_SIZE = 1000
DEFAULT_TRACEBACK_LEVEL = 'ERROR'
LOGGING_BROKEN_EXIT_CODE = 5
NORMAL_LOG_QUEUE_SIZE = 2
queue_size

Number of log records in the queue.

records_lost

Number of logging records that have been lost while the queue was full.

reload_config(config: Dict[str, Any]) → None

Apply log related configuration.

Note

It is also able to deal with runtime configuration changes.

Parameters:config – log section from Patroni configuration.
run() → None

Run logger’s thread main loop.

Keep consuming log queue until requested to quit through None special log record.

shutdown() → None

Shut down the logger thread.

update_loggers() → None

Configure loggers’ log level as defined in log.loggers section of Patroni configuration.

Note

It creates logger objects that are not defined yet in the log manager.

class patroni.log.ProxyHandler(patroni_logger: patroni.log.PatroniLogger)

Bases: logging.Handler

Handle log records in place of pending log handlers.

Note

This is used to handle log messages while the logger thread has not started yet, in which case the queue-based handler is not yet started.

Variables:patroni_logger – the logger thread.
emit(record: logging.LogRecord) → None

Emit each log record that is handled.

Will push the log record down to handle() method of the currently configured log handler.

Parameters:record – the record that was emitted.
class patroni.log.QueueHandler

Bases: logging.Handler

Queue-based logging handler.

Variables:queue – queue to hold log messages that are pending to be flushed to the final destination.
emit(record: logging.LogRecord) → None

Handle each log record that is emitted.

Call _put_record() to enqueue the emitted log record.

Also check if we have previously lost any log record, and if so, log a WARNING message.

Parameters:record – the record that was emitted.
records_lost

Number of log messages that have been lost while the queue was full.

patroni.log.debug_exception(self: logging.Logger, msg: object, *args, **kwargs) → None

Add full stack trace info to debug log messages and partial to others.

Handle exception() calls for self.

Note

  • If self log level is set to DEBUG, then issue a DEBUG message with the complete stack trace;
  • If self log level is INFO or higher, then issue an ERROR message with only the last line of
    the stack trace.
Parameters:
  • self – logger for which exception() will be processed.
  • msg – the message related to the exception to be logged.
  • args – positional arguments to be passed to debug() or error().
  • kwargs – keyword arguments to be passed to debug() or error().
patroni.log.error_exception(self: logging.Logger, msg: object, *args, **kwargs) → None

Add full stack trace info to error messages.

Handle exception() calls for self.

Note

  • By default issue an ERROR message with the complete stack trace. If you do not want to show the complete stack trace, call with exc_info=False.
Parameters:
  • self – logger for which exception() will be processed.
  • msg – the message related to the exception to be logged.
  • args – positional arguments to be passed to error().
  • kwargs – keyword arguments to be passed to error().