A bug for log_dir

[yangsp5]

In runx.logx line 110

if not os.path.isdir(self.logdir):

change to this:

if not os.path.isdir(self.logdir) and self.rank0:

if not, it will make a lot of dirs

[ajtao]

I think there's certainly a race condition, which is not great, but i'm not sure anything destructive happens: i think the first rank to create the directory will create it, but the other ranks will see that the directory exists and they won't create it.

[yangsp5]

I think there's certainly a race condition, which is not great, but i'm not sure anything destructive happens: i think the first rank to create the directory will create it, but the other ranks will see that the directory exists and they won't create it.

What is the meaning of 'I think there's certainly a race condition, which is not great', I can't understand cause rusty English. And my idea is simple:

if we set rank in logx.initialize, the other rank will not generate log. Then, the directory should not be created.

And, when we use a lots of GPUs, for example 16. It will create 16 directories, but only one will write the log. So the other directories is meaningless