queuelogger: Add support for background log writing
Writing to the debug log can cause an unbounded delay due to disk IO. This is particularly so on embedded machines such as the Raspberry Pi that run on SD cards. These log writing delays can cause problems for the main processing threads. The new "queuelogger" code forwards all the main thread log messages to a queue, and a background thread writes the log messages from the queue to the destination file. This eliminates the IO delay from the main threads. Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
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@ -98,9 +98,11 @@ printer object calls, which frequently translate the actions to
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commands to be executed on the micro-controller (as declared via the
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DECL_COMMAND macro in the micro-controller code).
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There are three threads in the Klippy host code. The main thread
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There are four threads in the Klippy host code. The main thread
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handles incoming gcode commands. A second thread (which resides
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entirely in the **klippy/serialqueue.c** C code) handles low-level IO
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with the serial port. The third thread is used to process response
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messages from the micro-controller in the Python code (see
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**klippy/serialhdl.py**).
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**klippy/serialhdl.py**). The fourth thread writes debug messages to
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the log (see **klippy/queuelogger.py**) so that the other threads
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never block on log writes.
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@ -5,7 +5,7 @@
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#
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# This file may be distributed under the terms of the GNU GPLv3 license.
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import sys, optparse, ConfigParser, logging, time, threading
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import gcode, toolhead, util, mcu, fan, heater, extruder, reactor
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import gcode, toolhead, util, mcu, fan, heater, extruder, reactor, queuelogger
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class ConfigWrapper:
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def __init__(self, printer, section):
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@ -132,7 +132,7 @@ def main():
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opts.error("Incorrect number of arguments")
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conffile = args[0]
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debuginput = debugoutput = None
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debuginput = debugoutput = bglogger = None
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debuglevel = logging.INFO
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if options.verbose:
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@ -142,8 +142,7 @@ def main():
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if options.outputfile:
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debugoutput = open(options.outputfile, 'wb')
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if options.logfile:
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logoutput = open(options.logfile, 'wb')
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logging.basicConfig(stream=logoutput, level=debuglevel)
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bglogger = queuelogger.setup_bg_logging(options.logfile, debuglevel)
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else:
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logging.basicConfig(level=debuglevel)
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logging.info("Starting Klippy...")
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@ -159,5 +158,8 @@ def main():
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store_dictionary(options.write_dictionary, printer)
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printer.run()
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if bglogger is not None:
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bglogger.stop()
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if __name__ == '__main__':
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main()
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@ -0,0 +1,48 @@
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# Code to implement asynchronous logging from a background thread
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#
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# Copyright (C) 2016 Kevin O'Connor <kevin@koconnor.net>
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#
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# This file may be distributed under the terms of the GNU GPLv3 license.
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import logging, threading, Queue
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# Class to forward all messages through a queue to a background thread
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class QueueHandler(logging.Handler):
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def __init__(self, queue):
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logging.Handler.__init__(self)
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self.queue = queue
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def emit(self, record):
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try:
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self.format(record)
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record.msg = record.message
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record.args = None
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record.exc_info = None
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self.queue.put_nowait(record)
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except Exception:
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self.handleError(record)
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# Class to poll a queue in a background thread and log each message
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class QueueListener(object):
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def __init__(self, handler):
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self.handler = handler
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self.queue = Queue.Queue()
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self.thread = threading.Thread(target=self._bg_thread)
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self.thread.start()
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def _bg_thread(self):
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while 1:
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record = self.queue.get(True)
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if record is None:
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break
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self.handler.handle(record)
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def stop(self):
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self.queue.put_nowait(None)
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self.thread.join()
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def setup_bg_logging(filename, debuglevel):
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logoutput = open(filename, 'wb')
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handler = logging.StreamHandler(logoutput)
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ql = QueueListener(handler)
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qh = QueueHandler(ql.queue)
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root = logging.getLogger()
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root.addHandler(qh)
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root.setLevel(debuglevel)
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return ql
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