Python logging use milliseconds in time format

Question

By default logging Formatter    asctime s   prints with the following format   2011-06-09 10 54 40 638   where 638 is the millisecond  I need to change the comma to a dot   2011-06-09 10 54 40 638   To format the time I can use   logging Formatter fmt    asctime s  datestr date format str    however the documentation doesn t specify how to format milliseconds  I ve found this SO question which talks about microseconds  but a  I would prefer milliseconds and b  the following doesn t work on Python 2 6  which I m working on  due to the  f   logging Formatter fmt    asctime s  datefmt   Y- m- d  H  M  S  f

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tl dr for folks looking here for an ISO formatted date  instead of using something like   Y- m- d  H  M  S  03d z   create your own class as   unutbu indicated  Here s one for iso date format  import logging from time import gmtime  strftime  class ISOFormatter logging Formatter       def formatTime self  record  datefmt None           t   strftime  quot  Y- m- dT H  M  S quot   gmtime record created           z   strftime  quot  z quot  gmtime record created           s    quot  s  03d s quot     t  record msecs z                  return s  logger   logging getLogger   name    logger setLevel logging DEBUG   console   logging StreamHandler   logger addHandler console   formatter   ISOFormatter fmt    asctime s -   module s -   levelname s -   message s   console setFormatter formatter   logger debug  Jackdaws love my big sphinx of quartz     2020-10-23T17 25 48 310-0800 -  lt stdin gt  - DEBUG - Jackdaws love my big sphinx of quartz

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Please note Craig McDaniel s solution is clearly better     logging Formatter s formatTime method looks like this   def formatTime self  record  datefmt None       ct   self converter record created      if datefmt          s   time strftime datefmt  ct      else          t   time strftime   Y- m- d  H  M  S   ct          s     s  03d     t  record msecs      return s   Notice the comma in   s  03d   This can not be fixed by specifying a datefmt because ct is a time struct time and these objects do not record milliseconds    If we change the definition of ct to make it a datetime object instead of a struct time  then  at least with modern versions of Python  we can call ct strftime and then we can use  f to format microseconds   import logging import datetime as dt  class MyFormatter logging Formatter       converter dt datetime fromtimestamp     def formatTime self  record  datefmt None           ct   self converter record created          if datefmt              s   ct strftime datefmt          else              t   ct strftime   Y- m- d  H  M  S               s     s  03d     t  record msecs          return s  logger   logging getLogger   name    logger setLevel logging DEBUG   console   logging StreamHandler   logger addHandler console   formatter   MyFormatter fmt    asctime s   message s  datefmt   Y- m- d  H  M  S  f   console setFormatter formatter   logger debug  Jackdaws love my big sphinx of quartz      2011-06-09 07 12 36 553554 Jackdaws love my big sphinx of quartz      Or  to get milliseconds  change the comma to a decimal point  and omit the datefmt argument   class MyFormatter logging Formatter       converter dt datetime fromtimestamp     def formatTime self  record  datefmt None           ct   self converter record created          if datefmt              s   ct strftime datefmt          else              t   ct strftime   Y- m- d  H  M  S               s     s  03d     t  record msecs          return s      formatter   MyFormatter fmt    asctime s   message s       logger debug  Jackdaws love my big sphinx of quartz      2011-06-09 08 14 38 343 Jackdaws love my big sphinx of quartz

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Many outdated  over-complicated and weird answers here  The reason is that the documentation is inadequate and the simple solution is to just use basicConfig   and set it as follows  logging basicConfig datefmt   Y- m- d  H  M  S   format   asctime   msecs 0 lt 3 0f   name   threadName   levelname    message    style       The trick here was that you have to also set the datefmt argument  as the default messes it up and is not what is  currently  shown in the how-to python docs  So rather look here   An alternative and possibly cleaner way  would have been to override the default msec format variable with  formatter   logging Formatter    asctime s   formatter default msec format     s  03d   However  that did not work for unknown reasons  PS  I am using Python 3 8

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The simplest way I found was to override default msec format   formatter   logging Formatter    asctime s   formatter default msec format     s  03d

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A simple expansion that doesn t require the datetime module and isn t handicapped like some other solutions is to use simple string replacement like so  import logging import time  class MyFormatter logging Formatter       def formatTime self  record  datefmt None           ct   self converter record created          if datefmt              if  quot  F quot  in datefmt                  msec    quot  03d quot    record msecs                 datefmt   datefmt replace  quot  F quot   msec              s   time strftime datefmt  ct          else              t   time strftime  quot  Y- m- d  H  M  S quot   ct              s    quot  s  03d quot     t  record msecs          return s  This way a date format can be written however you want  even allowing for region differences  by using  F for milliseconds  For example  log   logging getLogger   name    log setLevel logging INFO   sh   logging StreamHandler   log addHandler sh   fm   MyFormatter fmt    asctime s-  levelname s-  message s  datefmt   H  M  S  F   sh setFormatter fm   log info  quot Foo  Bar  Baz quot     03 26 33 757-INFO-Foo  Bar  Baz

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After instantiating a Formatter I usually set formatter converter   gmtime  So in order for  unutbu s answer to work in this case you ll need   class MyFormatter logging Formatter       def formatTime self  record  datefmt None           ct   self converter record created          if datefmt              s   time strftime datefmt  ct          else              t   time strftime   Y- m- d  H  M  S   ct              s     s  03d     t  record msecs          return s

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This should work too    logging Formatter fmt    asctime s   msecs 03d  datefmt   Y- m- d  H  M  S

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As of now the following works perfectly with python 3             logging basicConfig level logging DEBUG                       format    asctime s   levelname -8s   message s                        datefmt   Y  m  d  H  M  S  03d                        filename self log filepath                       filemode  w     gives the following output     2020 01 11 18 51 19 011 INFO

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If you are using arrow or if you don t mind using arrow  You can substitute python s time formatting for arrow s one   import logging  from arrow arrow import Arrow   class ArrowTimeFormatter logging Formatter        def formatTime self  record  datefmt None           arrow time   Arrow fromtimestamp record created           if datefmt              arrow time   arrow time format datefmt           return str arrow time    logger   logging getLogger   name     default handler   logging StreamHandler   default handler setFormatter ArrowTimeFormatter      fmt    asctime s       datefmt  YYYY-MM-DD HH mm ss SSS      logger setLevel logging DEBUG  logger addHandler default handler    Now you can use all of arrow s time formatting in datefmt attribute

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Adding msecs was the better option  Thanks  Here is my amendment using this with Python 3 5 3 in Blender  import logging logging basicConfig level logging DEBUG  format    asctime s   msecs 03d   levelname s  t  message s   datefmt   Y- m- d  H  M  S   log   logging getLogger   name    log info  Logging Info   log debug  Logging Debug

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If you prefer to use style      fmt  quot  asctime   msecs 0 lt 3 0f  quot  will 0-pad your microseconds to three places for consistency

[python] Python logging: use milliseconds in time format

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