DataModule: Explicit Barrier Needed Between prepare_data and setup for Multi-GPU

[piyushumate]

Hello, I am actually new to lightning.

I have the following structure for my project.

DataModule(Lightning):
      self.prepare_data_per_node = True
      
def prepare_data():
        #downloading a big file 
        #file_path = (saved to tmp)
        
def setup():
        #reading from the file

I have a single node multi GPU setup. In the other ranks in setup, its saying that the file doesn't exist (after download). Do I need to add barrier to synchronize so that all ranks (and processes) will eventually have access to the file?