[Train] Add flags to disable creating log directories

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• I had searched in the issues and found no similar feature requirement.

Description

In order to prototype tune/rllib integration and assess its performance, we would need to disable expensive file io operations that aren’t necessary during the training loop.

Right now, I can probably redirect training logs to /tmp directory, but I don’t know how expensive these file operations are. Perhaps they aren’t all that expensive if I don’t actually add any log data via train.report. @matthewdeng @amogkam wdyt?

Use case

RLlib/tune integration

Related issues

No response

Are you willing to submit a PR?

• Yes I am willing to submit a PR!

[matthewdeng]

train.report() calls aren’t actually logged unless you pass in a logging Callback (e.g. JsonLoggerCallback).

[amogkam]

cc @JiahaoYao