Don't duplicate frozen parameters during predict() #20851
Merged
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On the Jax backend we were not using donate_argnums during
predict()
. This works when a model is mostly trainable, but when a model is mostly or all frozen, this will result in 2x the memory jump (which is why we use donate_argnums for fit and evaluate).This change adds
donate_argnums
to the predict function to avoid the memory spike. But because this means all incoming state (including the trainable variables) will be deleted by jax, this means we need to sync the trainable variables state much like in fit and evaluate. An alternative would be to change the predict_step signature (so we could only donate non-trainable variables), but this would be a breaking change and confusing.