I have noticed so much spam in my log files with the message in the thread title. What is it missing? I have installed the en_US locale on my operating system (which is FreeBSD).
2)
Is there a possibility to log certain data from my controller into one, specified file (not folder-separated by date)?
1) Change the configured locate to the correct one. Check what the exact locale is, on some OS'ses it is called "en_US.utf8" for example.
2) Just use the File class to open a file and write to it? Or if you need more features, create a second instance of Monolog (which we use for logging), and configure it the way you want?