I'm not using torch launch, but the launch function in https://github.com/facebookresearch/detectron2/blob/master/detectron2/engine/launch.py I placed Task.init(...) inside the "main_func" that gets called in mp.spawn.
Meant to get back to you a bit sooner, but I can report that I no longer have duplicate tasks after updating to 0.13.4rc0 and putting Task.init in those two places. The job hasn't run to completion, so I can't report if it ends cleanly or not.
No manual logging attempted Tensorboard, terminal outputs, and argparser log properly No longer need the "-W ignore" arguments
So the way it will work, is you will also need to have a Task.init in main process (the one using the launch function) and the same Task.init in the main_func. What it does is it signals the sub processes to use the main process task. This way they all report to the same task. Obviously to test it you will need to wait for the RC (after the weekend :)