[RLlib] Issue 21297: Ignore PPO KL-loss term completely if kl-coeff == 0.0 to avoid NaN values due to some discrete action probs==0.0 #21456
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2 tasks
gjoliver
approved these changes
Jan 7, 2022
| policy.config["vf_loss_coeff"] * vf_loss - | ||
| policy.entropy_coeff * curr_entropy) | ||
| # Add mean_kl_loss (already processed through `reduce_mean_valid`), | ||
| # if necessary. | ||
| if policy.config["kl_coeff"] > 0.0: |
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seems this if statement is not necessary, 0.0 case, mean_kl_loss is zero. same below.
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Normally, yes, but if the calculated kl is Inf (due to some actions having almost 0.0 probability -> log(a) = -inf), then multiplying it with 0.0 will result in NaN. :)
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sorry, wasn't clear enough.
I mean if policy.config["kl_coeff"] <= 0.0, mean_kl_loss is hardcoded to be 0.0 now.
so it seems like we don't really need to have this particular if statement here.
the above one is critical, for sure.
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Issue 21297: Ignore PPO KL-loss term completely if kl-coeff == 0.0 to avoid NaN values due to some discrete action probs==0.0
Why are these changes needed?
#21297
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