Function log_metrics

src/transformers/trainer_pt_utils.py:830–917

Log metrics in a specially formatted way. Under distributed environment this is done only for a process with rank 0. Args: split (`str`): Mode/split name: one of `train`, `eval`, `test` metrics (`dict[str, float]`): The metrics returned from tra

(self, split, metrics)

# Trainer helper method: imported into the Trainer class and used as a method (takes `self` as first argument).
def log_metrics(self, split, metrics):
    """
    Log metrics in a specially formatted way.

    Under distributed environment this is done only for a process with rank 0.

    Args:
        split (`str`):
            Mode/split name: one of `train`, `eval`, `test`
        metrics (`dict[str, float]`):
            The metrics returned from train/evaluate/predictmetrics: metrics dict

    Notes on memory reports:

    In order to get memory usage report you need to install `psutil`. You can do that with `pip install psutil`.

    Now when this method is run, you will see a report that will include:

    ```
    init_mem_cpu_alloc_delta   =     1301MB
    init_mem_cpu_peaked_delta  =      154MB
    init_mem_gpu_alloc_delta   =      230MB
    init_mem_gpu_peaked_delta  =        0MB
    train_mem_cpu_alloc_delta  =     1345MB
    train_mem_cpu_peaked_delta =        0MB
    train_mem_gpu_alloc_delta  =      693MB
    train_mem_gpu_peaked_delta =        7MB
    ```

    **Understanding the reports:**

    - the first segment, e.g., `train__`, tells you which stage the metrics are for. Reports starting with `init_`
        will be added to the first stage that gets run. So that if only evaluation is run, the memory usage for the
        `__init__` will be reported along with the `eval_` metrics.
    - the third segment, is either `cpu` or `gpu`, tells you whether it's the general RAM or the gpu0 memory
        metric.
    - `*_alloc_delta` - is the difference in the used/allocated memory counter between the end and the start of the
        stage - it can be negative if a function released more memory than it allocated.
    - `*_peaked_delta` - is any extra memory that was consumed and then freed - relative to the current allocated
        memory counter - it is never negative. When you look at the metrics of any stage you add up `alloc_delta` +
        `peaked_delta` and you know how much memory was needed to complete that stage.

    The reporting happens only for process of rank 0 and gpu 0 (if there is a gpu). Typically this is enough since the
    main process does the bulk of work, but it could be not quite so if model parallel is used and then other GPUs may
    use a different amount of gpu memory. This is also not the same under DataParallel where gpu0 may require much more
    memory than the rest since it stores the gradient and optimizer states for all participating GPUs. Perhaps in the
    future these reports will evolve to measure those too.

    The CPU RAM metric measures RSS (Resident Set Size) includes both the memory which is unique to the process and the
    memory shared with other processes. It is important to note that it does not include swapped out memory, so the
    reports could be imprecise.

    The CPU peak memory is measured using a sampling thread. Due to python's GIL it may miss some of the peak memory if
    that thread didn't get a chance to run when the highest memory was used. Therefore this report can be less than
    reality. Using `tracemalloc` would have reported the exact peak memory, but it doesn't report memory allocations
    outside of python. So if some C++ CUDA extension allocated its own memory it won't be reported. And therefore it
    was dropped in favor of the memory sampling approach, which reads the current process memory usage.