logging format contains process id and thread name also

[gccode1]

It seems to be useful to add process id and thread name in logging. By using this we can distinguish between logging of different processes and different threads which is very useful in debugging.

[josiahcarlson]

I like where you are going with this (the ability to change / update the logging message format), but I can't change everyone's logging output going forward without explicitly letting them opt-in.

How are you calling rpqueue? I can probably pull information out of the system environment via os.environ, have a command-line argument --logfmt, or if you need this during load/import, I can probably push all of the logging initialization (and reading of log format config) until after the module has been loaded.