cancel downloads for deleted instances (#1393)

after deleting an instance, if a given (node_id, model_id) pair doesn't exist in the left over instances, cancel the download of model_id on node_id.

justfile

@@ -20,7 +20,7 @@ sync-clean:
 
 rust-rebuild:
     cargo run --bin stub_gen
-    just sync-clean
+    uv sync --reinstall-package exo_pyo3_bindings
 
 build-dashboard:
     #!/usr/bin/env bash

pyproject.toml

@@ -19,7 +19,7 @@ dependencies = [
     "anyio==4.11.0",
     "mlx==0.30.4; sys_platform == 'darwin'",
     "mlx[cpu]==0.30.4; sys_platform == 'linux'",
-    "mlx-lm==0.30.6",
+    "mlx-lm",
     "tiktoken>=0.12.0", # required for kimi k2 tokenizer
     "hypercorn>=0.18.0",
     "openai-harmony>=0.0.8",
@@ -63,6 +63,7 @@ members = [
 
 [tool.uv.sources]
 exo_pyo3_bindings = { workspace = true }
+mlx-lm = { git = "https://github.com/ml-explore/mlx-lm", branch = "main" }
 # Uncomment to use local mlx/mlx-lm development versions:
 # mlx = { path = "/Users/Shared/mlx", editable=true }
 # mlx-lm = { path = "/Users/Shared/mlx-lm", editable=true }

src/exo/download/coordinator.py

@@ -16,6 +16,7 @@ from exo.download.download_utils import (
 from exo.download.shard_downloader import ShardDownloader
 from exo.shared.models.model_cards import ModelId
 from exo.shared.types.commands import (
+    CancelDownload,
     DeleteDownload,
     ForwarderDownloadCommand,
     StartDownload,
@@ -107,6 +108,13 @@ class DownloadCoordinator:
                         await self._start_download(shard)
                     case DeleteDownload(model_id=model_id):
                         await self._delete_download(model_id)
+                    case CancelDownload(model_id=model_id):
+                        await self._cancel_download(model_id)
+
+    async def _cancel_download(self, model_id: ModelId) -> None:
+        if model_id in self.active_downloads and model_id in self.download_status:
+            logger.info(f"Cancelling download for {model_id}")
+            self.active_downloads.pop(model_id).cancel()
 
     async def _start_download(self, shard: ShardMetadata) -> None:
         model_id = shard.model_card.model_id

src/exo/main.py

@@ -105,6 +105,7 @@ class Node:
             global_event_sender=router.sender(topics.GLOBAL_EVENTS),
             local_event_receiver=router.receiver(topics.LOCAL_EVENTS),
             command_receiver=router.receiver(topics.COMMANDS),
+            download_command_sender=router.sender(topics.DOWNLOAD_COMMANDS),
         )
 
         er_send, er_recv = channel[ElectionResult]()
@@ -188,6 +189,9 @@ class Node:
                         global_event_sender=self.router.sender(topics.GLOBAL_EVENTS),
                         local_event_receiver=self.router.receiver(topics.LOCAL_EVENTS),
                         command_receiver=self.router.receiver(topics.COMMANDS),
+                        download_command_sender=self.router.sender(
+                            topics.DOWNLOAD_COMMANDS
+                        ),
                     )
                     self._tg.start_soon(self.master.run)
                 elif (

src/exo/master/main.py

@@ -6,6 +6,7 @@ from loguru import logger
 
 from exo.master.placement import (
     add_instance_to_placements,
+    cancel_unnecessary_downloads,
     delete_instance,
     get_transition_events,
     place_instance,
@@ -16,6 +17,7 @@ from exo.shared.types.commands import (
     CreateInstance,
     DeleteInstance,
     ForwarderCommand,
+    ForwarderDownloadCommand,
     ImageEdits,
     ImageGeneration,
     PlaceInstance,
@@ -66,12 +68,9 @@ class Master:
         session_id: SessionId,
         *,
         command_receiver: Receiver[ForwarderCommand],
-        # Receiving indexed events from the forwarder to be applied to state
-        # Ideally these would be WorkerForwarderEvents but type system says no :(
         local_event_receiver: Receiver[ForwarderEvent],
-        # Send events to the forwarder to be indexed (usually from command processing)
-        # Ideally these would be MasterForwarderEvents but type system says no :(
         global_event_sender: Sender[ForwarderEvent],
+        download_command_sender: Sender[ForwarderDownloadCommand],
     ):
         self.state = State()
         self._tg: TaskGroup = anyio.create_task_group()
@@ -81,6 +80,7 @@ class Master:
         self.command_receiver = command_receiver
         self.local_event_receiver = local_event_receiver
         self.global_event_sender = global_event_sender
+        self.download_command_sender = download_command_sender
         send, recv = channel[Event]()
         self.event_sender: Sender[Event] = send
         self._loopback_event_receiver: Receiver[Event] = recv
@@ -280,6 +280,14 @@ class Master:
                             transition_events = get_transition_events(
                                 self.state.instances, placement
                             )
+                            for cmd in cancel_unnecessary_downloads(
+                                placement, self.state.downloads
+                            ):
+                                await self.download_command_sender.send(
+                                    ForwarderDownloadCommand(
+                                        origin=self.node_id, command=cmd
+                                    )
+                                )
                             generated_events.extend(transition_events)
                         case PlaceInstance():
                             placement = place_instance(

src/exo/master/placement.py

@@ -15,14 +15,20 @@ from exo.master.placement_utils import (
 from exo.shared.models.model_cards import ModelId
 from exo.shared.topology import Topology
 from exo.shared.types.commands import (
+    CancelDownload,
     CreateInstance,
     DeleteInstance,
+    DownloadCommand,
     PlaceInstance,
 )
 from exo.shared.types.common import NodeId
 from exo.shared.types.events import Event, InstanceCreated, InstanceDeleted
 from exo.shared.types.memory import Memory
 from exo.shared.types.profiling import MemoryUsage, NodeNetworkInfo
+from exo.shared.types.worker.downloads import (
+    DownloadOngoing,
+    DownloadProgress,
+)
 from exo.shared.types.worker.instances import (
     Instance,
     InstanceId,
@@ -202,3 +208,29 @@ def get_transition_events(
             )
 
     return events
+
+
+def cancel_unnecessary_downloads(
+    instances: Mapping[InstanceId, Instance],
+    download_status: Mapping[NodeId, Sequence[DownloadProgress]],
+) -> Sequence[DownloadCommand]:
+    commands: list[DownloadCommand] = []
+    currently_downloading = [
+        (k, v.shard_metadata.model_card.model_id)
+        for k, vs in download_status.items()
+        for v in vs
+        if isinstance(v, (DownloadOngoing))
+    ]
+    active_models = set(
+        (
+            node_id,
+            instance.shard_assignments.runner_to_shard[runner_id].model_card.model_id,
+        )
+        for instance in instances.values()
+        for node_id, runner_id in instance.shard_assignments.node_to_runner.items()
+    )
+    for pair in currently_downloading:
+        if pair not in active_models:
+            commands.append(CancelDownload(target_node_id=pair[0], model_id=pair[1]))
+
+    return commands

src/exo/master/tests/test_master.py

@@ -11,6 +11,7 @@ from exo.shared.models.model_cards import ModelCard, ModelTask
 from exo.shared.types.commands import (
     CommandId,
     ForwarderCommand,
+    ForwarderDownloadCommand,
     PlaceInstance,
     TextGeneration,
 )
@@ -47,6 +48,7 @@ async def test_master():
     ge_sender, global_event_receiver = channel[ForwarderEvent]()
     command_sender, co_receiver = channel[ForwarderCommand]()
     local_event_sender, le_receiver = channel[ForwarderEvent]()
+    fcds, _fcdr = channel[ForwarderDownloadCommand]()
 
     all_events: list[IndexedEvent] = []
 
@@ -67,6 +69,7 @@ async def test_master():
         global_event_sender=ge_sender,
         local_event_receiver=le_receiver,
         command_receiver=co_receiver,
+        download_command_sender=fcds,
     )
     logger.info("run the master")
     async with anyio.create_task_group() as tg:

src/exo/shared/types/commands.py

@@ -72,7 +72,12 @@ class DeleteDownload(BaseCommand):
     model_id: ModelId
 
 
-DownloadCommand = StartDownload | DeleteDownload
+class CancelDownload(BaseCommand):
+    target_node_id: NodeId
+    model_id: ModelId
+
+
+DownloadCommand = StartDownload | DeleteDownload | CancelDownload
 
 
 Command = (

tests/run_exo_on.sh

@@ -35,7 +35,7 @@ i=0
 for host; do
   colour=${colours[i++ % 4]}
   ssh -T -o BatchMode=yes -o ServerAliveInterval=30 "$host@$host" \
-    "/nix/var/nix/profiles/default/bin/nix run github:exo-explore/exo/$commit" |&
+    "EXO_LIBP2P_NAMESPACE=$commit /nix/var/nix/profiles/default/bin/nix run github:exo-explore/exo/$commit" |&
     awk -v p="${colour}[${host}]${reset}" '{ print p $0; fflush() }' &
 done
 

uv.lock

@@ -415,7 +415,7 @@ requires-dist = [
     { name = "mflux", specifier = "==0.15.4" },
     { name = "mlx", marker = "sys_platform == 'darwin'", specifier = "==0.30.4" },
     { name = "mlx", extras = ["cpu"], marker = "sys_platform == 'linux'", specifier = "==0.30.4" },
-    { name = "mlx-lm", specifier = "==0.30.6" },
+    { name = "mlx-lm", git = "https://github.com/ml-explore/mlx-lm?branch=main" },
     { name = "openai-harmony", specifier = ">=0.0.8" },
     { name = "pillow", specifier = ">=11.0,<12.0" },
     { name = "psutil", specifier = ">=7.0.0" },
@@ -1072,8 +1072,8 @@ wheels = [
 
 [[package]]
 name = "mlx-lm"
-version = "0.30.6"
-source = { registry = "https://pypi.org/simple" }
+version = "0.30.5"
+source = { git = "https://github.com/ml-explore/mlx-lm?branch=main#96699e6dadb13b82b28285bb131a0741997d19ae" }
 dependencies = [
     { name = "jinja2", marker = "sys_platform == 'darwin' or sys_platform == 'linux'" },
     { name = "mlx", marker = "sys_platform == 'darwin'" },
@@ -1083,10 +1083,6 @@ dependencies = [
     { name = "sentencepiece", marker = "sys_platform == 'darwin' or sys_platform == 'linux'" },
     { name = "transformers", marker = "sys_platform == 'darwin' or sys_platform == 'linux'" },
 ]
-sdist = { url = "https://files.pythonhosted.org/packages/76/cb/815deddc8699b1f694d7e1f9cbed52934c03a8b49432c8add72932bb2f0b/mlx_lm-0.30.6.tar.gz", hash = "sha256:807e042d7040268f1b19190b7eaefd8b2efbff5590a65460974ad4225b91dda1", size = 271733 }
-wheels = [
-    { url = "https://files.pythonhosted.org/packages/20/5f/01d281f1fa8a1521d5936659beb4f5ab1f32b463d059263cf9d4cef969d9/mlx_lm-0.30.6-py3-none-any.whl", hash = "sha256:a7405bd581eacc4bf8209d7a6b7f23629585a0d7c6740c2a97e51fee35b3b0e1", size = 379451 },
-]
 
 [[package]]
 name = "mlx-metal"