Prologue -Webframework - How to set thread-local variables for logging when compiling with `--threads:on` flag?

Question

I am writing a web-application in nim, using the web-framework prologue and the ORM norm. I've found that the log-messages of prologue and norm that normally appear in the terminal when starting up the application disappear, when you compile with the --threads:on flag.

That is because log-message-handlers and log levels are set as thread-local variables, so when a new thread is created the log-level must be set for that thread again etc.

However, prologue is the one instantiating the threads, so how do I properly set this up for every thread that prologue creates?

Answer 1

I found the answer thanks to the help of prologue's creator: xflywind.

The answer is prologue-events. When prologue creates a thread, it triggers a list of procs, so called events, that are registered on startup. All you need to do is define an event that sets the log-level and provides a handler.

proc setLoggingLevel() =
  addHandler(newConsoleLogger())
  logging.setLogFilter(lvlDebug)

let 
  event = initEvent(setLoggingLevel)

var
  app = newApp(settings = settings, startup = @[event])