diff options
Diffstat (limited to 'Lib')
| -rw-r--r-- | Lib/logging/handlers.py | 52 |
1 files changed, 52 insertions, 0 deletions
diff --git a/Lib/logging/handlers.py b/Lib/logging/handlers.py index 332aefc..487cdd5 100644 --- a/Lib/logging/handlers.py +++ b/Lib/logging/handlers.py @@ -1134,3 +1134,55 @@ class MemoryHandler(BufferingHandler): self.flush() self.target = None BufferingHandler.close(self) + + +class QueueHandler(logging.Handler): + """ + This handler sends events to a queue. Typically, it would be used together + with a multiprocessing Queue to centralise logging to file in one process + (in a multi-process application), so as to avoid file write contention + between processes. + + This code is new in Python 3.2, but this class can be copy pasted into + user code for use with earlier Python versions. + """ + + def __init__(self, queue): + """ + Initialise an instance, using the passed queue. + """ + logging.Handler.__init__(self) + self.queue = queue + + def enqueue(self, record): + """ + Enqueue a record. + + The base implementation uses put_nowait. You may want to override + this method if you want to use blocking, timeouts or custom queue + implementations. + """ + self.queue.put_nowait(record) + + def emit(self, record): + """ + Emit a record. + + Writes the LogRecord to the queue, preparing it for pickling first. + """ + try: + # The format operation gets traceback text into record.exc_text + # (if there's exception data), and also puts the message into + # record.message. We can then use this to replace the original + # msg + args, as these might be unpickleable. We also zap the + # exc_info attribute, as it's no longer needed and, if not None, + # will typically not be pickleable. + self.format(record) + record.msg = record.message + record.args = None + record.exc_info = None + self.enqueue(record) + except (KeyboardInterrupt, SystemExit): + raise + except: + self.handleError(record) |