performance.rst

Performance

structlog's default configuration tries to be as unsurprising and not confusing to new developers as possible. Some of the choices made come with an avoidable performance price tag -- although its impact is debatable.

Here are a few hints how to get most out of structlog in production:

1. Use plain dicts as context classes. Python is full of them and they are highly optimized:

   configure(context_class=dict)

   If you don't use automated parsing (you should!) and need predicable order of your keys for some reason, use the key_order argument of ~structlog.processors.KeyValueRenderer.

2. Use a specific wrapper class instead of the generic one. structlog comes with ones for the standard-library and for twisted:

   configure(wrapper_class=structlog.stdlib.BoundLogger)

   Writing own wrapper classes <custom-wrappers> is straightforward too.

3. Avoid (frequently) calling log methods on loggers you get back from structlog.wrap_logger and structlog.get_logger. Since those functions are usually called in module scope and thus before you are able to configure them, they return a proxy that assembles the correct logger on demand.

   Create a local logger if you expect to log frequently without binding:

   logger = structlog.get_logger()
   def f():
      log = logger.bind()
      for i in range(1000000000):
         log.info('iterated', i=i)

4. Set the cache_logger_on_first_use option to True so the aforementioned on-demand loggers will be assembled only once and cached for future uses:

   configure(cache_logger_on_first_use=True)

   This has the only drawback is that later calls on ~structlog.configure don't have any effect on already cached loggers -- that shouldn't matter outside of testing though.