def mpi_bcast_jax(x, *, token=None, root, comm=MPI_jax_comm):
if n_nodes == 1:
assert root == 0
return x, token
else:
import mpi4jax
return mpi4jax.bcast(x, token=token, root=root, comm=comm)
def test_bcast_scalar_jit():
from mpi4jax import bcast
arr = 1
_arr = 1
if rank != 0:
_arr = _arr * 0
res = jax.jit(lambda x: bcast(x, root=0)[0])(_arr)
assert jnp.array_equal(res, arr)
if rank == 0:
assert jnp.array_equal(_arr, arr)
def test_bcast_scalar():
from mpi4jax import bcast
arr = 1
_arr = 1
if rank != 0:
_arr = _arr * 0
res, token = bcast(_arr, root=0)
assert jnp.array_equal(res, arr)
if rank == 0:
assert jnp.array_equal(_arr, arr)
def test_bcast_jit():
from mpi4jax import bcast
arr = jnp.ones((3, 2))
_arr = arr.copy()
if rank != 0:
_arr = _arr * 0
res = jax.jit(lambda x: bcast(x, root=0)[0])(arr)
assert jnp.array_equal(res, arr)
if rank == 0:
assert jnp.array_equal(_arr, arr)
def test_bcast():
from mpi4jax import bcast
arr = jnp.ones((3, 2))
_arr = arr.copy()
if rank != 0:
_arr = _arr * 0
res, token = bcast(_arr, root=0)
assert jnp.array_equal(res, arr)
if rank == 0:
assert jnp.array_equal(_arr, arr)
def PRNGKey(
seed: Optional[SeedT] = None, root: int = 0, comm=MPI.COMM_WORLD
) -> PRNGKeyT:
"""
Initialises a PRNGKey using an optional starting seed.
The same seed will be distributed to all processes.
"""
if seed is None:
key = jax.random.PRNGKey(random_seed())
elif isinstance(seed, int):
key = jax.random.PRNGKey(seed)
else:
key = seed
if n_nodes > 1:
import mpi4jax
key, _ = mpi4jax.bcast(key, root=root, comm=comm)
return key
def mpi_split(key, root=0, comm=MPI.COMM_WORLD) -> PRNGKeyT:
"""
Split a key across MPI nodes in the communicator.
Only the input key on the root process matters.
Arguments:
key: The key to split. Only considered the one on the root process.
root: (default=0) The root rank from which to take the input key.
comm: (default=MPI.COMM_WORLD) The MPI communicator.
Returns:
A PRNGKey depending on rank number and key.
"""
# Maybe add error/warning if in_key is not the same
# on all MPI nodes?
keys = jax.random.split(key, n_nodes)
if n_nodes > 1:
import mpi4jax
keys, _ = mpi4jax.bcast(keys, root=root, comm=comm)
return keys[rank]
