File logging in a thread using spawn (GC safe call expression)

[Isofruit]

I think a small code sample could help here, because I'm not sure where logger 
comes from. You can just log like this (handler creation was moved into a 
gcsafe proc to prove that its gcsafe):
    
    
    import std/[asyncdispatch, os, sugar, logging]
    
    proc setupLogger() {.gcsafe.} =
      addHandler(newConsoleLogger(levelThreshold = lvlDebug))
    
    proc a() {.gcsafe.} =
      debug "Starting Callbacks"
    
    setupLogger()
    a()
    
    
    Run

No access to global state necessary. You'll need that per thread as each 
handler is per thread, but that all works.