feat: Initial commit

utils/comm.py

@@ -0,0 +1,192 @@
+"""
+The code is base on https://github.com/Pointcept/Pointcept
+"""
+
+import functools
+import numpy as np
+import torch
+import torch.distributed as dist
+
+_LOCAL_PROCESS_GROUP = None
+"""
+A torch process group which only includes processes that on the same machine as the current process.
+This variable is set when processes are spawned by `launch()` in "engine/launch.py".
+"""
+
+
+def get_world_size() -> int:
+    if not dist.is_available():
+        return 1
+    if not dist.is_initialized():
+        return 1
+    return dist.get_world_size()
+
+
+def get_rank() -> int:
+    if not dist.is_available():
+        return 0
+    if not dist.is_initialized():
+        return 0
+    return dist.get_rank()
+
+
+def get_local_rank() -> int:
+    """
+    Returns:
+        The rank of the current process within the local (per-machine) process group.
+    """
+    if not dist.is_available():
+        return 0
+    if not dist.is_initialized():
+        return 0
+    assert (
+        _LOCAL_PROCESS_GROUP is not None
+    ), "Local process group is not created! Please use launch() to spawn processes!"
+    return dist.get_rank(group=_LOCAL_PROCESS_GROUP)
+
+
+def get_local_size() -> int:
+    """
+    Returns:
+        The size of the per-machine process group,
+        i.e. the number of processes per machine.
+    """
+    if not dist.is_available():
+        return 1
+    if not dist.is_initialized():
+        return 1
+    return dist.get_world_size(group=_LOCAL_PROCESS_GROUP)
+
+
+def is_main_process() -> bool:
+    return get_rank() == 0
+
+
+def synchronize():
+    """
+    Helper function to synchronize (barrier) among all processes when
+    using distributed training
+    """
+    if not dist.is_available():
+        return
+    if not dist.is_initialized():
+        return
+    world_size = dist.get_world_size()
+    if world_size == 1:
+        return
+    if dist.get_backend() == dist.Backend.NCCL:
+        # This argument is needed to avoid warnings.
+        # It's valid only for NCCL backend.
+        dist.barrier(device_ids=[torch.cuda.current_device()])
+    else:
+        dist.barrier()
+
+
+@functools.lru_cache()
+def _get_global_gloo_group():
+    """
+    Return a process group based on gloo backend, containing all the ranks
+    The result is cached.
+    """
+    if dist.get_backend() == "nccl":
+        return dist.new_group(backend="gloo")
+    else:
+        return dist.group.WORLD
+
+
+def all_gather(data, group=None):
+    """
+    Run all_gather on arbitrary picklable data (not necessarily tensors).
+    Args:
+        data: any picklable object
+        group: a torch process group. By default, will use a group which
+            contains all ranks on gloo backend.
+    Returns:
+        list[data]: list of data gathered from each rank
+    """
+    if get_world_size() == 1:
+        return [data]
+    if group is None:
+        group = (
+            _get_global_gloo_group()
+        )  # use CPU group by default, to reduce GPU RAM usage.
+    world_size = dist.get_world_size(group)
+    if world_size == 1:
+        return [data]
+
+    output = [None for _ in range(world_size)]
+    dist.all_gather_object(output, data, group=group)
+    return output
+
+
+def gather(data, dst=0, group=None):
+    """
+    Run gather on arbitrary picklable data (not necessarily tensors).
+    Args:
+        data: any picklable object
+        dst (int): destination rank
+        group: a torch process group. By default, will use a group which
+            contains all ranks on gloo backend.
+    Returns:
+        list[data]: on dst, a list of data gathered from each rank. Otherwise,
+            an empty list.
+    """
+    if get_world_size() == 1:
+        return [data]
+    if group is None:
+        group = _get_global_gloo_group()
+    world_size = dist.get_world_size(group=group)
+    if world_size == 1:
+        return [data]
+    rank = dist.get_rank(group=group)
+
+    if rank == dst:
+        output = [None for _ in range(world_size)]
+        dist.gather_object(data, output, dst=dst, group=group)
+        return output
+    else:
+        dist.gather_object(data, None, dst=dst, group=group)
+        return []
+
+
+def shared_random_seed():
+    """
+    Returns:
+        int: a random number that is the same across all workers.
+        If workers need a shared RNG, they can use this shared seed to
+        create one.
+    All workers must call this function, otherwise it will deadlock.
+    """
+    ints = np.random.randint(2**31)
+    all_ints = all_gather(ints)
+    return all_ints[0]
+
+
+def reduce_dict(input_dict, average=True):
+    """
+    Reduce the values in the dictionary from all processes so that process with rank
+    0 has the reduced results.
+    Args:
+        input_dict (dict): inputs to be reduced. All the values must be scalar CUDA Tensor.
+        average (bool): whether to do average or sum
+    Returns:
+        a dict with the same keys as input_dict, after reduction.
+    """
+    world_size = get_world_size()
+    if world_size < 2:
+        return input_dict
+    with torch.no_grad():
+        names = []
+        values = []
+        # sort the keys so that they are consistent across processes
+        for k in sorted(input_dict.keys()):
+            names.append(k)
+            values.append(input_dict[k])
+        values = torch.stack(values, dim=0)
+        dist.reduce(values, dst=0)
+        if dist.get_rank() == 0 and average:
+            # only main process gets accumulated, so only divide by
+            # world_size in this case
+            values /= world_size
+        reduced_dict = {k: v for k, v in zip(names, values)}
+    return reduced_dict