fix: --no-downloads no longer blocks model loading (#1510 )

When --no-downloads is passed, skip download checks in plan() so pre-staged models can be loaded without DownloadCompleted events. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Leo/address rdma gpu locks 2 (#1515 )
2026-02-18 14:55:13 -05:00 · 2026-02-17 14:40:12 -08:00 · 2026-02-17 14:00:52 -08:00
10 changed files with 123 additions and 48 deletions
--- a/README.md
+++ b/README.md
@@ -72,16 +72,23 @@ There are two ways to run exo:

 ### Run from Source (macOS)

+If you have [Nix](https://nixos.org/) installed, you can skip most of the steps below and run exo directly (after accepting the Cachix cache):
+
+```bash
+nix run .#exo
+```
+
 **Prerequisites:**
+- [Xcode](https://developer.apple.com/xcode/) (provides the Metal ToolChain required for MLX compilation)
 - [brew](https://github.com/Homebrew/brew) (for simple package management on macOS)
-  
+
  ```bash
  /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
  ```
 - [uv](https://github.com/astral-sh/uv) (for Python dependency management)
 - [macmon](https://github.com/vladkens/macmon) (for hardware monitoring on Apple Silicon)
 - [node](https://github.com/nodejs/node) (for building the dashboard)
-  
+
  ```bash
  brew install uv macmon node
  ```
--- a/flake.nix
+++ b/flake.nix
@@ -115,7 +115,7 @@
          packages = lib.optionalAttrs pkgs.stdenv.hostPlatform.isDarwin (
            let
              uvLock = builtins.fromTOML (builtins.readFile ./uv.lock);
-              mlxPackage = builtins.head (builtins.filter (p: p.name == "mlx") uvLock.package);
+              mlxPackage = builtins.head (builtins.filter (p: p.name == "mlx" && p.source ? git) uvLock.package);
              uvLockMlxVersion = mlxPackage.version;
            in
            {
--- a/nix/mlx.nix
+++ b/nix/mlx.nix
@@ -41,16 +41,16 @@ let

  mlx = stdenv.mkDerivation rec {
    pname = "mlx";
-    version = let v = "0.30.6"; in
+    version = let v = "0.30.7.dev20260217+50487b41"; in
      assert v == uvLockMlxVersion || throw "MLX version mismatch: nix/mlx.nix has ${v} but uv.lock has ${uvLockMlxVersion}. Update both the version and hash in nix/mlx.nix.";
      v;
    pyproject = true;

    src = fetchFromGitHub {
-      owner = "ml-explore";
-      repo = "mlx";
-      tag = "v${version}";
-      hash = "sha256-avD5EGhwgmPdXLAyQSqTO6AXk/W3ziH+f6AetjK3Sdo=";
+      owner = "rltakashige";
+      repo = "mlx-jaccl-fix-small-recv";
+      rev = "50487b4141f3c951122655db3b83df5146c1fbeb";
+      hash = "sha256-IL4a9vMX5nocgJU1WG4zE8hArHkHJtnh4sdYh3od5zU=";
    };

    patches = [
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -17,7 +17,7 @@ dependencies = [
    "loguru>=0.7.3",
    "exo_pyo3_bindings", # rust bindings
    "anyio==4.11.0",
-    "mlx==0.30.6; sys_platform == 'darwin'",
+    "mlx; sys_platform == 'darwin'",
    "mlx[cpu]==0.30.6; sys_platform == 'linux'",
    "mlx-lm==0.30.6",
    "tiktoken>=0.12.0", # required for kimi k2 tokenizer
@@ -64,6 +64,7 @@ members = [

 [tool.uv.sources]
 exo_pyo3_bindings = { workspace = true }
+mlx = { git = "https://github.com/rltakashige/mlx-jaccl-fix-small-recv.git", branch = "address-rdma-gpu-locks", marker = "sys_platform == 'darwin'" }
 #mlx-lm = { git = "https://github.com/davidmcc73/mlx-lm", branch = "stable" }
 # Uncomment to use local mlx/mlx-lm development versions:
 # mlx = { path = "/Users/Shared/mlx", editable=true }
--- a/python/parts.nix
+++ b/python/parts.nix
@@ -58,6 +58,21 @@
        lib.optionalAttrs pkgs.stdenv.hostPlatform.isLinux (
          (lib.mapAttrs (_: ignoreMissing) nvidiaPackages) // {
            mlx = ignoreMissing prev.mlx;
+            mlx-cuda-13 = prev.mlx-cuda-13.overrideAttrs (old: {
+              buildInputs = (old.buildInputs or [ ]) ++ [
+                final.nvidia-cublas
+                final.nvidia-cuda-nvrtc
+                final.nvidia-cudnn-cu13
+                final.nvidia-nccl-cu13
+              ];
+              preFixup = ''
+                addAutoPatchelfSearchPath ${final.nvidia-cublas}
+                addAutoPatchelfSearchPath ${final.nvidia-cuda-nvrtc}
+                addAutoPatchelfSearchPath ${final.nvidia-cudnn-cu13}
+                addAutoPatchelfSearchPath ${final.nvidia-nccl-cu13}
+              '';
+              autoPatchelfIgnoreMissingDeps = [ "libcuda.so.1" ];
+            });
            torch = ignoreMissing prev.torch;
            triton = ignoreMissing prev.triton;
          }
@@ -74,14 +89,25 @@
          linuxOverlay
        ]
      );
-      exoVenv = pythonSet.mkVirtualEnv "exo-env" workspace.deps.default;
+      # mlx-cpu and mlx-cuda-13 both ship mlx/ site-packages files; keep first.
+      # mlx-cpu/mlx-cuda-13 and nvidia-cudnn-cu12/cu13 ship overlapping files.
+      venvCollisionPaths = lib.optionals pkgs.stdenv.hostPlatform.isLinux [
+        "lib/python3.13/site-packages/mlx*"
+        "lib/python3.13/site-packages/nvidia*"
+      ];
+
+      exoVenv = (pythonSet.mkVirtualEnv "exo-env" workspace.deps.default).overrideAttrs {
+        venvIgnoreCollisions = venvCollisionPaths;
+      };

      # Virtual environment with dev dependencies for testing
-      testVenv = pythonSet.mkVirtualEnv "exo-test-env" (
+      testVenv = (pythonSet.mkVirtualEnv "exo-test-env" (
        workspace.deps.default // {
          exo = [ "dev" ]; # Include pytest, pytest-asyncio, pytest-env
        }
-      );
+      )).overrideAttrs {
+        venvIgnoreCollisions = venvCollisionPaths;
+      };

      mkPythonScript = name: path: pkgs.writeShellApplication {
        inherit name;
--- a/src/exo/main.py
+++ b/src/exo/main.py
@@ -94,6 +94,7 @@ class Node:
                command_sender=router.sender(topics.COMMANDS),
                download_command_sender=router.sender(topics.DOWNLOAD_COMMANDS),
                event_index_counter=event_index_counter,
+                no_downloads=args.no_downloads,
            )
        else:
            worker = None
@@ -225,6 +226,7 @@ class Node:
                        )
                        self._tg.start_soon(self.download_coordinator.run)
                    if self.worker:
+                        no_downloads = self.worker.no_downloads
                        self.worker.shutdown()
                        # TODO: add profiling etc to resource monitor
                        self.worker = Worker(
@@ -239,6 +241,7 @@ class Node:
                                topics.DOWNLOAD_COMMANDS
                            ),
                            event_index_counter=self.event_index_counter,
+                            no_downloads=no_downloads,
                        )
                        self._tg.start_soon(self.worker.run)
                    if self.api:
--- a/src/exo/worker/main.py
+++ b/src/exo/worker/main.py
@@ -65,6 +65,7 @@ class Worker:
        command_sender: Sender[ForwarderCommand],
        download_command_sender: Sender[ForwarderDownloadCommand],
        event_index_counter: Iterator[int],
+        no_downloads: bool = False,
    ):
        self.node_id: NodeId = node_id
        self.session_id: SessionId = session_id
@@ -74,6 +75,7 @@ class Worker:
        self.event_index_counter = event_index_counter
        self.command_sender = command_sender
        self.download_command_sender = download_command_sender
+        self.no_downloads = no_downloads
        self.event_buffer = OrderedBuffer[Event]()
        self.out_for_delivery: dict[EventId, ForwarderEvent] = {}

@@ -182,6 +184,7 @@ class Worker:
                self.state.tasks,
                self.input_chunk_buffer,
                self.input_chunk_counts,
+                no_downloads=self.no_downloads,
            )
            if task is None:
                continue
--- a/src/exo/worker/plan.py
+++ b/src/exo/worker/plan.py
@@ -51,15 +51,20 @@ def plan(
    tasks: Mapping[TaskId, Task],
    input_chunk_buffer: Mapping[CommandId, dict[int, str]] | None = None,
    input_chunk_counts: Mapping[CommandId, int] | None = None,
+    no_downloads: bool = False,
 ) -> Task | None:
    # Python short circuiting OR logic should evaluate these sequentially.
    return (
        _cancel_tasks(runners, tasks)
        or _kill_runner(runners, all_runners, instances)
        or _create_runner(node_id, runners, instances)
-        or _model_needs_download(node_id, runners, global_download_status)
+        or (
+            None
+            if no_downloads
+            else _model_needs_download(node_id, runners, global_download_status)
+        )
        or _init_distributed_backend(runners, all_runners)
-        or _load_model(runners, all_runners, global_download_status)
+        or _load_model(runners, all_runners, global_download_status, no_downloads)
        or _ready_to_warmup(runners, all_runners)
        or _pending_tasks(runners, tasks, all_runners, input_chunk_buffer or {})
    )
@@ -192,22 +197,25 @@ def _load_model(
    runners: Mapping[RunnerId, RunnerSupervisor],
    all_runners: Mapping[RunnerId, RunnerStatus],
    global_download_status: Mapping[NodeId, Sequence[DownloadProgress]],
+    no_downloads: bool = False,
 ) -> LoadModel | None:
    for runner in runners.values():
        instance = runner.bound_instance.instance
        shard_assignments = instance.shard_assignments

-        all_local_downloads_complete = all(
-            nid in global_download_status
-            and any(
-                isinstance(dp, DownloadCompleted)
-                and dp.shard_metadata.model_card.model_id == shard_assignments.model_id
-                for dp in global_download_status[nid]
+        if not no_downloads:
+            all_local_downloads_complete = all(
+                nid in global_download_status
+                and any(
+                    isinstance(dp, DownloadCompleted)
+                    and dp.shard_metadata.model_card.model_id
+                    == shard_assignments.model_id
+                    for dp in global_download_status[nid]
+                )
+                for nid in shard_assignments.node_to_runner
            )
-            for nid in shard_assignments.node_to_runner
-        )
-        if not all_local_downloads_complete:
-            continue
+            if not all_local_downloads_complete:
+                continue

        is_single_node_instance = len(instance.shard_assignments.runner_to_shard) == 1
        if is_single_node_instance and isinstance(runner.status, RunnerIdle):
--- a/src/exo/worker/tests/unittests/test_plan/test_download_and_loading.py
+++ b/src/exo/worker/tests/unittests/test_plan/test_download_and_loading.py
@@ -157,6 +157,41 @@ def test_plan_does_not_request_download_when_shard_already_downloaded():
    assert not isinstance(result, plan_mod.DownloadModel)


+def test_plan_loads_model_with_no_downloads_flag():
+    """
+    When no_downloads=True, plan() should skip download checks and proceed
+    to load the model even with empty global_download_status.
+    """
+    shard = get_pipeline_shard_metadata(model_id=MODEL_A_ID, device_rank=0)
+    instance = get_mlx_ring_instance(
+        instance_id=INSTANCE_1_ID,
+        model_id=MODEL_A_ID,
+        node_to_runner={NODE_A: RUNNER_1_ID},
+        runner_to_shard={RUNNER_1_ID: shard},
+    )
+    bound_instance = BoundInstance(
+        instance=instance, bound_runner_id=RUNNER_1_ID, bound_node_id=NODE_A
+    )
+    runner = FakeRunnerSupervisor(bound_instance=bound_instance, status=RunnerIdle())
+
+    runners = {RUNNER_1_ID: runner}
+    instances = {INSTANCE_1_ID: instance}
+    all_runners = {RUNNER_1_ID: RunnerIdle()}
+
+    result = plan_mod.plan(
+        node_id=NODE_A,
+        runners=runners,  # type: ignore
+        global_download_status={},
+        instances=instances,
+        all_runners=all_runners,
+        tasks={},
+        no_downloads=True,
+    )
+
+    assert isinstance(result, LoadModel)
+    assert result.instance_id == INSTANCE_1_ID
+
+
 def test_plan_does_not_load_model_until_all_shards_downloaded_globally():
    """
    LoadModel should not be emitted while some shards are still missing from
--- a/uv.lock
+++ b/uv.lock
@@ -377,8 +377,8 @@ dependencies = [
    { name = "hypercorn", marker = "sys_platform == 'darwin' or sys_platform == 'linux'" },
    { name = "loguru", marker = "sys_platform == 'darwin' or sys_platform == 'linux'" },
    { name = "mflux", marker = "sys_platform == 'darwin' or sys_platform == 'linux'" },
-    { name = "mlx", marker = "sys_platform == 'darwin' or sys_platform == 'linux'" },
-    { name = "mlx", extra = ["cpu"], marker = "sys_platform == 'linux'" },
+    { name = "mlx", version = "0.30.6", source = { registry = "https://pypi.org/simple" }, extra = ["cpu"], marker = "sys_platform == 'linux'" },
+    { name = "mlx", version = "0.30.7.dev20260217+50487b41", source = { git = "https://github.com/rltakashige/mlx-jaccl-fix-small-recv.git?branch=address-rdma-gpu-locks#50487b4141f3c951122655db3b83df5146c1fbeb" }, marker = "sys_platform == 'darwin'" },
    { name = "mlx-lm", marker = "sys_platform == 'darwin' or sys_platform == 'linux'" },
    { name = "msgspec", marker = "sys_platform == 'darwin' or sys_platform == 'linux'" },
    { name = "openai-harmony", marker = "sys_platform == 'darwin' or sys_platform == 'linux'" },
@@ -416,7 +416,7 @@ requires-dist = [
    { name = "hypercorn", specifier = ">=0.18.0" },
    { name = "loguru", specifier = ">=0.7.3" },
    { name = "mflux", specifier = "==0.15.5" },
-    { name = "mlx", marker = "sys_platform == 'darwin'", specifier = "==0.30.6" },
+    { name = "mlx", marker = "sys_platform == 'darwin'", git = "https://github.com/rltakashige/mlx-jaccl-fix-small-recv.git?branch=address-rdma-gpu-locks" },
    { name = "mlx", extras = ["cpu"], marker = "sys_platform == 'linux'", specifier = "==0.30.6" },
    { name = "mlx-lm", specifier = "==0.30.6" },
    { name = "msgspec", specifier = ">=0.19.0" },
@@ -1020,8 +1020,8 @@ dependencies = [
    { name = "fonttools", marker = "sys_platform == 'darwin' or sys_platform == 'linux'" },
    { name = "huggingface-hub", marker = "sys_platform == 'darwin' or sys_platform == 'linux'" },
    { name = "matplotlib", marker = "sys_platform == 'darwin' or sys_platform == 'linux'" },
-    { name = "mlx", marker = "sys_platform == 'darwin' or sys_platform == 'linux'" },
-    { name = "mlx", extra = ["cuda13"], marker = "sys_platform == 'linux'" },
+    { name = "mlx", version = "0.30.6", source = { registry = "https://pypi.org/simple" }, extra = ["cuda13"], marker = "sys_platform == 'linux'" },
+    { name = "mlx", version = "0.30.7.dev20260217+50487b41", source = { git = "https://github.com/rltakashige/mlx-jaccl-fix-small-recv.git?branch=address-rdma-gpu-locks#50487b4141f3c951122655db3b83df5146c1fbeb" }, marker = "sys_platform == 'darwin'" },
    { name = "numpy", marker = "sys_platform == 'darwin' or sys_platform == 'linux'" },
    { name = "opencv-python", marker = "sys_platform == 'darwin' or sys_platform == 'linux'" },
    { name = "piexif", marker = "sys_platform == 'darwin' or sys_platform == 'linux'" },
@@ -1048,18 +1048,12 @@ wheels = [
 name = "mlx"
 version = "0.30.6"
 source = { registry = "https://pypi.org/simple" }
-dependencies = [
-    { name = "mlx-metal", marker = "sys_platform == 'darwin'" },
+resolution-markers = [
+    "sys_platform == 'linux'",
 ]
 wheels = [
-    { url = "https://files.pythonhosted.org/packages/ae/5b/e460e144a34d5529e010056cccf50b538d56ed001473bc6b246018fd58cb/mlx-0.30.6-cp313-cp313-macosx_14_0_arm64.whl", hash = "sha256:ed86f8bffc174c2f259ca589ea25464c96cf69d1bb457074a2bf2ef53737e54f", size = 573515, upload-time = "2026-02-06T03:45:23.405Z" },
-    { url = "https://files.pythonhosted.org/packages/60/25/69833fefb9a3fef30b56792b1bcd022496c4fea83e45411d289b77ef7546/mlx-0.30.6-cp313-cp313-macosx_15_0_arm64.whl", hash = "sha256:c52294958269e20f300639a17c1900ca8fc737d859ddda737f9811e94bd040e5", size = 573516, upload-time = "2026-02-06T03:45:24.618Z" },
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 ]
@@ -1072,6 +1066,14 @@ cuda13 = [
    { name = "mlx-cuda-13", marker = "sys_platform == 'linux'" },
 ]

+[[package]]
+name = "mlx"
+version = "0.30.7.dev20260217+50487b41"
+source = { git = "https://github.com/rltakashige/mlx-jaccl-fix-small-recv.git?branch=address-rdma-gpu-locks#50487b4141f3c951122655db3b83df5146c1fbeb" }
+resolution-markers = [
+    "sys_platform == 'darwin'",
+]
+
 [[package]]
 name = "mlx-cpu"
 version = "0.30.6"
@@ -1102,7 +1104,7 @@ version = "0.30.6"
 source = { registry = "https://pypi.org/simple" }
 dependencies = [
    { name = "jinja2", marker = "sys_platform == 'darwin' or sys_platform == 'linux'" },
-    { name = "mlx", marker = "sys_platform == 'darwin'" },
+    { name = "mlx", version = "0.30.7.dev20260217+50487b41", source = { git = "https://github.com/rltakashige/mlx-jaccl-fix-small-recv.git?branch=address-rdma-gpu-locks#50487b4141f3c951122655db3b83df5146c1fbeb" }, marker = "sys_platform == 'darwin'" },
    { name = "numpy", marker = "sys_platform == 'darwin' or sys_platform == 'linux'" },
    { name = "protobuf", marker = "sys_platform == 'darwin' or sys_platform == 'linux'" },
    { name = "pyyaml", marker = "sys_platform == 'darwin' or sys_platform == 'linux'" },
@@ -1114,16 +1116,6 @@ wheels = [
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 ]

-[[package]]
-name = "mlx-metal"
-version = "0.30.6"
-source = { registry = "https://pypi.org/simple" }
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