Function fit

verl/examples/split_placement/split_monkey_patch.py:38–237

The training loop of PPO. The driver process only need to call the compute functions of the worker group through RPC to construct the PPO dataflow. The light-weight advantage computation is done on the driver process.

(self)

def fit(self):
    """
    The training loop of PPO.
    The driver process only need to call the compute functions of the worker group through RPC
    to construct the PPO dataflow.
    The light-weight advantage computation is done on the driver process.
    """
    from omegaconf import OmegaConf

    from verl.utils.tracking import Tracking

    logger = Tracking(
        project_name=self.config.trainer.project_name,
        experiment_name=self.config.trainer.experiment_name,
        default_backend=self.config.trainer.logger,
        config=OmegaConf.to_container(self.config, resolve=True),
    )

    self.global_steps = 0

    # load checkpoint before doing anything
    self._load_checkpoint()

    # perform validation before training
    # currently, we only support validation using the reward_function.
    if self.val_reward_fn is not None and self.config.trainer.get("val_before_train", True):
        val_metrics = self._validate()
        pprint(f"Initial validation metrics: {val_metrics}")
        logger.log(data=val_metrics, step=self.global_steps)
        if self.config.trainer.get("val_only", False):
            return

    # we start from step 1
    self.global_steps += 1
    last_val_metrics = None

    for epoch in range(self.config.trainer.total_epochs):
        for batch_dict in self.train_dataloader:
            metrics = {}
            timing_raw = {}

            batch: DataProto = DataProto.from_single_dict(batch_dict)

            # pop those keys for generation
            gen_batch = batch.pop(batch_keys=["input_ids", "attention_mask", "position_ids"])
            is_last_step = self.global_steps >= self.total_training_steps

            with marked_timer("step", timing_raw):
                # generate a batch
                with marked_timer("gen", timing_raw):
                    gen_batch_output = self.actor_rollout_wg.generate_sequences(gen_batch)
                    timing_raw.update(gen_batch_output.meta_info["timing"])
                    gen_batch_output.meta_info.pop("timing", None)

                if self.config.algorithm.adv_estimator == AdvantageEstimator.REMAX:
                    with marked_timer("gen_max", timing_raw):
                        gen_baseline_batch = deepcopy(gen_batch)
                        gen_baseline_batch.meta_info["do_sample"] = False