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Move shard_map doc to use Explicit mode and Auto mode. #33191

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Nov 8, 2025
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Merged

Move shard_map doc to use Explicit mode and Auto mode. #33191

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75 changes: 51 additions & 24 deletions docs/notebooks/shard_map.ipynb
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Original file line number Diff line number Diff line change
Expand Up @@ -55,7 +55,9 @@
"import jax\n",
"import jax.numpy as jnp\n",
"\n",
"from jax.sharding import Mesh, PartitionSpec as P"
"from jax.sharding import Mesh, PartitionSpec as P\n",
"Explicit = jax.sharding.AxisType.Explicit\n",
"Auto = jax.sharding.AxisType.Auto"
]
},
{
Expand All @@ -65,12 +67,13 @@
"metadata": {},
"outputs": [],
"source": [
"mesh = jax.make_mesh((4, 2), ('x', 'y'))\n",
"mesh = jax.make_mesh((4, 2), ('x', 'y'), axis_types=(Explicit,) * 2)\n",
"jax.set_mesh(mesh)\n",
"\n",
"a = jnp.arange( 8 * 16.).reshape(8, 16)\n",
"b = jnp.arange(16 * 4.).reshape(16, 4)\n",
"\n",
"@jax.shard_map(mesh=mesh, in_specs=(P('x', 'y'), P('y', None)),\n",
"@jax.shard_map(in_specs=(P('x', 'y'), P('y', None)),\n",
" out_specs=P('x', None))\n",
"def matmul_basic(a_block, b_block):\n",
" # a_block: f32[2, 8]\n",
Expand Down Expand Up @@ -148,16 +151,15 @@
"source": [
"from jax.sharding import NamedSharding\n",
"\n",
"a = jax.device_put(a, NamedSharding(mesh, P('x', 'y')))\n",
"b = jax.device_put(b, NamedSharding(mesh, P('y', None)))\n",
"a = jax.device_put(a, P('x', 'y'))\n",
"b = jax.device_put(b, P('y', None))\n",
"\n",
"@jax.jit\n",
"def matmul_reference(a, b):\n",
" c = jnp.dot(a, b)\n",
" return jax.lax.with_sharding_constraint(c, NamedSharding(mesh, P('x', None)))\n",
" return jnp.dot(a, b, out_sharding=P('x', None))\n",
"\n",
"c_ref = matmul_reference(a, b)\n",
"allclose(c_ref, jnp.dot(a, b))"
"allclose(c_ref, jnp.dot(a, b, out_sharding=P('x', None)))"
]
},
{
Expand Down Expand Up @@ -245,7 +247,8 @@
"source": [
"import numpy as np\n",
"devices = np.array(jax.devices()[:4])\n",
"mesh = Mesh(devices, ('i',)) # mesh.shape['i'] = 4\n",
"mesh = Mesh(devices, ('i',), axis_types=(Explicit,)) # mesh.shape['i'] = 4\n",
"jax.set_mesh(mesh)\n",
"\n",
"def check_shmap(f, y):\n",
" ans = jax.shard_map(f, mesh=mesh, in_specs=P('i'), out_specs=P('i'))(y)\n",
Expand Down Expand Up @@ -293,7 +296,8 @@
"metadata": {},
"outputs": [],
"source": [
"mesh = jax.make_mesh((4, 2), ('i', 'j'))\n",
"mesh = jax.make_mesh((4, 2), ('i', 'j'), axis_types=(Auto,) * 2)\n",
"jax.set_mesh(mesh)\n",
"\n",
"@jax.shard_map(mesh=mesh, in_specs=P('i', None), out_specs=P('i', 'j'))\n",
"def f1(x_block):\n",
Expand Down Expand Up @@ -494,7 +498,8 @@
"metadata": {},
"outputs": [],
"source": [
"mesh = jax.make_mesh((2,), ('i',))\n",
"mesh = jax.make_mesh((2,), ('i',), axis_types=(Explicit,))\n",
"jax.set_mesh(mesh)\n",
"\n",
"@jax.shard_map(mesh=mesh, in_specs=P('i'), out_specs=P('i'))\n",
"def f(x):\n",
Expand Down Expand Up @@ -607,7 +612,8 @@
"metadata": {},
"outputs": [],
"source": [
"mesh = jax.make_mesh((4, 2), ('i', 'j'))\n",
"mesh = jax.make_mesh((4, 2), ('i', 'j'), axis_types=(Explicit,) * 2)\n",
"jax.set_mesh(mesh)\n",
"\n",
"@jax.shard_map(mesh=mesh, in_specs=P('i', 'j'), out_specs=P('i'))\n",
"def f(x):\n",
Expand Down Expand Up @@ -645,7 +651,8 @@
"metadata": {},
"outputs": [],
"source": [
"mesh = jax.make_mesh((2,), ('i',))\n",
"mesh = jax.make_mesh((2,), ('i',), axis_types=(Explicit,))\n",
"jax.set_mesh(mesh)\n",
"\n",
"x = jnp.arange(6.)\n",
"try:\n",
Expand Down Expand Up @@ -741,7 +748,8 @@
"metadata": {},
"outputs": [],
"source": [
"mesh = jax.make_mesh((2,), ('i',))\n",
"mesh = jax.make_mesh((2,), ('i',), axis_types=(Explicit,))\n",
"jax.set_mesh(mesh)\n",
"\n",
"@jax.shard_map(mesh=mesh, in_specs=(P('i'), P()), out_specs=P('i'))\n",
"def f(x, y):\n",
Expand Down Expand Up @@ -776,7 +784,8 @@
"metadata": {},
"outputs": [],
"source": [
"mesh = jax.make_mesh((2,), ('i',))\n",
"mesh = jax.make_mesh((2,), ('i',), axis_types=(Explicit,))\n",
"jax.set_mesh(mesh)\n",
"\n",
"@jax.shard_map(mesh=mesh, in_specs=(P('i'), P()), out_specs=P('i'))\n",
"def f(x, y):\n",
Expand Down Expand Up @@ -946,6 +955,7 @@
"outputs": [],
"source": [
"mesh1d = Mesh(jax.devices()[:4], ('i',))\n",
"jax.set_mesh(mesh1d)\n",
"\n",
"@jax.shard_map(mesh=mesh1d, in_specs=P('i'), out_specs=P(None))\n",
"def f1(x_block):\n",
Expand Down Expand Up @@ -1002,6 +1012,7 @@
"outputs": [],
"source": [
"mesh2d = Mesh(np.array(jax.devices()[:4]).reshape(2, 2), ('i', 'j'))\n",
"jax.set_mesh(mesh2d)\n",
"\n",
"@jax.shard_map(mesh=mesh2d, in_specs=P('i', 'j'), out_specs=P(None, 'j'))\n",
"def f2(x_block):\n",
Expand Down Expand Up @@ -1071,6 +1082,8 @@
"metadata": {},
"outputs": [],
"source": [
"jax.set_mesh(mesh1d)\n",
"\n",
"@jax.shard_map(mesh=mesh1d, in_specs=P('i'), out_specs=P('i'))\n",
"def f4(x_block):\n",
" print('BEFORE:\\n', x_block)\n",
Expand Down Expand Up @@ -1153,7 +1166,7 @@
"metadata": {},
"outputs": [],
"source": [
"@jax.shard_map(mesh=mesh1d, in_specs=P('i'), out_specs=P('i'))\n",
"@jax.shard_map(in_specs=P('i'), out_specs=P('i'))\n",
"def f6(x_block):\n",
" print('BEFORE:\\n', x_block)\n",
" y_block = jax.lax.psum_scatter(x_block, 'i', tiled=True)\n",
Expand Down Expand Up @@ -1229,7 +1242,7 @@
"metadata": {},
"outputs": [],
"source": [
"@jax.shard_map(mesh=mesh1d, in_specs=P('i'), out_specs=P('i'))\n",
"@jax.shard_map(in_specs=P('i'), out_specs=P('i'))\n",
"def f7(x_block):\n",
" sz = jax.lax.axis_size('i')\n",
" print('BEFORE:\\n', x_block)\n",
Expand Down Expand Up @@ -1307,7 +1320,7 @@
"metadata": {},
"outputs": [],
"source": [
"@jax.shard_map(mesh=mesh1d, in_specs=P('i'), out_specs=P('i'))\n",
"@jax.shard_map(in_specs=P('i'), out_specs=P('i'))\n",
"def f8(x_block):\n",
" print('BEFORE:\\n', x_block)\n",
" y_block = psum_scatter(x_block, 'i', tiled=True)\n",
Expand Down Expand Up @@ -1438,6 +1451,7 @@
"outputs": [],
"source": [
"mesh = Mesh(jax.devices()[:4], ('i',))\n",
"jax.set_mesh(mesh)\n",
"\n",
"def device_put(x, pspec):\n",
" return jax.device_put(x, NamedSharding(mesh, pspec))"
Expand Down Expand Up @@ -1884,7 +1898,8 @@
"source": [
"from jax.sharding import NamedSharding, Mesh, PartitionSpec as P\n",
"\n",
"mesh = jax.make_mesh((8,), ('batch',))\n",
"mesh = jax.make_mesh((8,), ('batch',), axis_types=(Auto,))\n",
"jax.set_mesh(mesh)\n",
"\n",
"# replicate initial params on all devices, shard data batch over devices\n",
"batch = jax.device_put(batch, NamedSharding(mesh, P('batch')))\n",
Expand Down Expand Up @@ -1982,6 +1997,7 @@
"source": [
"# shard data batch *and params* over devices\n",
"mesh = Mesh(devices, ('batch',))\n",
"jax.set_mesh(mesh)\n",
"batch = jax.device_put(batch, NamedSharding(mesh, P('batch')))\n",
"params = jax.device_put(params, NamedSharding(mesh, P('batch')))\n",
"\n",
Expand Down Expand Up @@ -2055,7 +2071,8 @@
"metadata": {},
"outputs": [],
"source": [
"mesh = jax.make_mesh((8,), ('feats',))\n",
"mesh = jax.make_mesh((8,), ('feats',), axis_types=(Auto,))\n",
"jax.set_mesh(mesh)\n",
"\n",
"batch = jax.device_put(batch, NamedSharding(mesh, P(None, 'feats')))\n",
"params = jax.device_put(params, NamedSharding(mesh, P('feats')))\n",
Expand Down Expand Up @@ -2096,7 +2113,8 @@
"metadata": {},
"outputs": [],
"source": [
"mesh = jax.make_mesh((4, 2), ('batch', 'feats'))\n",
"mesh = jax.make_mesh((4, 2), ('batch', 'feats'), axis_types=(Auto,) * 2)\n",
"jax.set_mesh(mesh)\n",
"\n",
"batch_ = jax.device_put(batch, NamedSharding(mesh, P('batch', 'feats')))\n",
"params_ = jax.device_put(params, NamedSharding(mesh, P(('batch', 'feats'))))\n",
Expand Down Expand Up @@ -2285,7 +2303,17 @@
"metadata": {},
"outputs": [],
"source": [
"print(jax.jit(loss)(params, batch))\n",
"print(jax.jit(loss)(params, batch))"
]
},
{
"cell_type": "code",
"execution_count": null,
"id": "9ff83661",
"metadata": {},
"outputs": [],
"source": [
"jax.set_mesh(mesh)\n",
"print(jax.jit(loss_pp)(params_, batch_))"
]
},
Expand All @@ -2303,8 +2331,7 @@
"metadata": {
"jupytext": {
"cell_metadata_filter": "-all",
"formats": "ipynb,md:myst",
"main_language": "python"
"formats": "ipynb,md:myst"
},
"kernelspec": {
"display_name": "Python 3",
Expand Down
63 changes: 42 additions & 21 deletions docs/notebooks/shard_map.md
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