Files
app/backend/fluksio/flow/remote.py
T
stroblmeandClaude Opus 5 1a9753fa9d Let a worker say what machine it is
A worker reported its labels and nothing about the machine behind them, so the
engine could route a node to a GPU box but not tell whether that box had a GPU
free. Inventory — cores, GPUs, memory — now arrives with the hello frame, and
the run frame carries back what the engine allocated for that call.

Which is protocol 2 on both ends. GPUs are never probed: asking a vendor tool
would make the one dependency two, so a GPU is what the batch job says it was
given or what --gpus says. A worker that reports nothing still attaches and is
scheduled by its label alone.

Two things a job scheduler needs: --max-idle stops a worker started for one job
rather than letting it hold its allocation to the walltime, and a refusal is now
fatal instead of a reconnect loop that reads as a hang in a job's log.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01A6HeySA27EkGANZN95QySW
2026-08-27 08:29:35 +02:00

441 lines
16 KiB
Python

"""Workers on other hosts, reached over a socket they opened themselves.
The engine runs where the automations are; a GPU sits somewhere else. Those
two are usually not on the same network, and the one that can be dialled is
the engine — so a worker connects *out* to it and the engine answers over the
connection it was given. That also means nothing has to expose Redis, which is
the thing a remote worker must never be handed.
What travels is the protocol the local worker pool already speaks: one JSON
object per line becomes one JSON frame, the node's source rides along with
every call so no code has to be distributed, and the reports a node makes
while it runs arrive the same way they do over a pipe. A node cannot tell
which kind of worker it is running on, which is the point — the same flow runs
in both places.
The awkward part is that the socket lives on the event loop and a node
executes on a worker thread. A call therefore hands its frame to the loop and
blocks on a queue of its own until the loop puts the answer there.
"""
from __future__ import annotations
import asyncio
import hashlib
import logging
import queue
import sys
import threading
import time
from collections.abc import Callable
from dataclasses import dataclass
from typing import Any
from fluksio.flow.nodes.base import NodeOutputError
from fluksio.flow.workers import NodeTimeout, RemoteError, _remote_class
logger = logging.getLogger(__name__)
#: How long the loop is given to accept a frame we are handing it.
SEND_TIMEOUT_S = 30.0
#: A worker that has said nothing at all for this long — not even a heartbeat —
#: is treated as gone. It beats every ten seconds while it is executing, so this
#: catches a dead socket rather than a slow node, and it is what bounds a call
#: whose node has no timeout of its own.
SILENCE_S = 90.0
#: Protocol version this engine speaks. A worker announcing anything else is
#: refused rather than half-understood.
PROTOCOL = 2
class NoWorker(RemoteError):
"""Nothing is attached that carries the label this node asked for."""
def _whole(value: Any, default: int) -> int:
"""An int from whatever a worker sent, or the default when it was junk."""
try:
return int(value)
except (TypeError, ValueError):
return default
@dataclass(frozen=True)
class WorkerInventory:
"""What an attached worker says it holds.
The defaults are a machine that runs one thing at a time and has no GPU,
so a worker reporting nothing is scheduled by its label alone — which is
how every worker was scheduled before any of them reported anything.
"""
cpus: int = 1
gpus: int = 0
ram_mb: int | None = None
@classmethod
def from_hello(cls, payload: Any) -> WorkerInventory:
"""Read what is understood and ignore the rest.
Unknown members are deliberately not an error: a worker that learns to
report something new must not need this engine taught about it first.
"""
if not isinstance(payload, dict):
return cls()
return cls(
cpus=max(1, _whole(payload.get("cpus"), 1)),
gpus=max(0, _whole(payload.get("gpus"), 0)),
ram_mb=_whole(payload.get("ram_mb"), 0) or None,
)
class RemoteWorker:
"""One attached worker, and the calls it has in flight."""
def __init__(
self,
name: str,
labels: list[str],
send: Callable[[dict[str, Any]], Any],
loop: asyncio.AbstractEventLoop,
max_parallel: int = 1,
info: dict[str, Any] | None = None,
inventory: WorkerInventory | None = None,
) -> None:
self.name = name
self.labels = set(labels)
self.info = info or {}
self.inventory = inventory or WorkerInventory()
self.attached_at = time.time()
self.last_seen = time.time()
self._send = send
self._loop = loop
self._slots = threading.Semaphore(max_parallel)
self.max_parallel = max_parallel
self._pending: dict[str, queue.Queue[dict[str, Any] | None]] = {}
self._lock = threading.Lock()
self._gone = False
# Source this worker has already loaded, by digest. A rebuild asks
# every device-bound node whether it compiles, and without this that
# is a network round trip each time — which is how attaching a GPU box
# makes rebuilding the flows slow enough to fail a health check. A
# worker that reconnects is a new object, so this empties with it.
self._compiled: set[str] = set()
# -------------------------------------------------------------------------
# From the socket's side, on the event loop
# -------------------------------------------------------------------------
def deliver(self, message: dict[str, Any]) -> None:
"""Hand a frame to whichever call is waiting for it."""
self.last_seen = time.time()
call_id = str(message.get("call_id") or "")
with self._lock:
inbox = self._pending.get(call_id)
if inbox is not None:
inbox.put(message)
def detach(self) -> None:
"""The socket closed: wake everything still waiting on it."""
self._gone = True
with self._lock:
inboxes = list(self._pending.values())
for inbox in inboxes:
# None is "no more answers are coming", which the caller turns into
# a failed node rather than a wait that never ends.
inbox.put(None)
# -------------------------------------------------------------------------
# From a node's side, on a worker thread
# -------------------------------------------------------------------------
def request(
self,
payload: dict[str, Any],
timeout: float,
on_event: Callable[[dict[str, Any]], None] | None = None,
) -> dict[str, Any]:
if self._gone:
raise RemoteError(f"worker '{self.name}' is no longer attached")
call_id = str(payload["call_id"])
inbox: queue.Queue[dict[str, Any] | None] = queue.Queue()
# Blocking here is the backpressure, exactly as taking a slot is in the
# local pool.
self._slots.acquire()
with self._lock:
self._pending[call_id] = inbox
try:
future = asyncio.run_coroutine_threadsafe(self._send(payload), self._loop)
future.result(timeout=SEND_TIMEOUT_S)
# The node's own deadline measures silence, so a node reporting its
# progress is never mistaken for a hung one. A heartbeat is not
# progress: it says the agent is alive, which is what SILENCE_S
# asks, and says nothing about the node — so it feeds the liveness
# bound below and never the node's own.
deadline = time.monotonic() + timeout if timeout > 0 else None
while True:
wait = SILENCE_S
if deadline is not None:
wait = min(SILENCE_S, deadline - time.monotonic())
try:
message = inbox.get(timeout=max(wait, 0.0))
except queue.Empty:
self.cancel(call_id)
if deadline is not None and time.monotonic() >= deadline:
raise NodeTimeout(
f"'{self.name}' was silent for {timeout}s"
) from None
raise RemoteError(
f"worker '{self.name}' sent nothing for "
f"{SILENCE_S:.0f}s and is presumed gone"
) from None
if message is None:
raise RemoteError(f"worker '{self.name}' went away mid-call")
kind = message.get("event")
if kind == "heartbeat":
continue
if kind:
if on_event is not None:
try:
on_event(message)
except NodeOutputError:
# A port the node never declared. Stop the call
# rather than let the rest of its emissions arrive.
self.cancel(call_id)
raise
except Exception:
logger.exception("Could not record a worker event")
if deadline is not None:
deadline = time.monotonic() + timeout
continue
return message
except Exception as exc:
if isinstance(exc, (NodeTimeout, RemoteError, NodeOutputError)):
raise
raise RemoteError(f"worker '{self.name}': {exc}") from exc
finally:
with self._lock:
self._pending.pop(call_id, None)
self._slots.release()
@property
def compiled(self) -> set[str]:
"""Digests of the source this worker has already loaded."""
return self._compiled
@property
def gone(self) -> bool:
return self._gone
@property
def in_flight(self) -> int:
"""Calls this worker has not answered yet."""
with self._lock:
return len(self._pending)
def calls_of(self, run_id: str) -> list[str]:
with self._lock:
return [call for call in self._pending if call.startswith(f"{run_id}:")]
def cancel(self, call_id: str) -> None:
"""Ask the worker to kill what it is running for this call."""
try:
asyncio.run_coroutine_threadsafe(
self._send({"op": "cancel", "call_id": call_id}), self._loop
).result(timeout=SEND_TIMEOUT_S)
except Exception:
logger.warning("Could not cancel '%s' on '%s'", call_id, self.name)
class RemoteWorkerHub:
"""Every attached worker, and which of them a node may run on."""
def __init__(self) -> None:
self._workers: dict[str, RemoteWorker] = {}
self._lock = threading.Lock()
# -------------------------------------------------------------------------
# Attachment
# -------------------------------------------------------------------------
def attach(self, worker: RemoteWorker) -> None:
with self._lock:
existing = self._workers.get(worker.name)
if existing is not None:
# A worker that reconnects after a network drop: the old socket
# is dead whether or not it has noticed yet.
existing.detach()
self._workers[worker.name] = worker
logger.info(
"Worker '%s' attached with labels %s", worker.name, sorted(worker.labels)
)
def detach(self, name: str) -> None:
with self._lock:
worker = self._workers.pop(name, None)
if worker is not None:
worker.detach()
logger.info("Worker '%s' detached", name)
def workers(self) -> list[RemoteWorker]:
with self._lock:
return list(self._workers.values())
def labels(self) -> set[str]:
"""Every label something attached right now carries."""
with self._lock:
return {
label for worker in self._workers.values() for label in worker.labels
}
def pick(self, label: str) -> RemoteWorker | None:
"""A worker carrying this label, least busy first.
Resolved per call rather than when the flow was built, so a worker that
attaches after a run was submitted picks the work up without anything
being rebuilt.
"""
with self._lock:
candidates = [
worker
for worker in self._workers.values()
if not worker.gone and (label == worker.name or label in worker.labels)
]
if not candidates:
return None
return min(candidates, key=lambda worker: worker.in_flight)
# -------------------------------------------------------------------------
# Running a node on one
# -------------------------------------------------------------------------
def run(
self,
label: str,
flow: str,
node: str,
source: str,
kwargs: dict[str, Any],
node_id: str,
timeout: float,
run_id: str = "",
on_event: Callable[[dict[str, Any]], None] | None = None,
env: dict[str, str] | None = None,
) -> Any:
worker = self.pick(label)
if worker is None:
raise NoWorker(f"no worker labelled '{label}' is attached")
payload = {
"op": "run",
"call_id": f"{run_id}:{node_id}" if run_id else node_id,
"flow": flow,
"node": node,
"source": source,
"kwargs": kwargs,
"run": {"id": run_id} if run_id else None,
"timeout": timeout,
}
if env:
# What this call was allocated: the thread caps and the devices the
# node may see. The worker starts a process per call, so it applies
# them where a library still reads them — before the import.
payload["env"] = env
response = worker.request(
payload,
timeout=timeout,
on_event=on_event,
)
logs = response.get("logs")
if logs:
sys.stdout.write(logs)
if response.get("ok"):
return response.get("result")
error = response.get("error") or {}
raise _remote_class(str(error.get("type") or "RemoteError"))(
str(error.get("message") or "the node failed"),
str(error.get("traceback") or ""),
)
def compile(
self, label: str, flow: str, node: str, source: str, timeout: float = 60.0
) -> str | None:
"""Load this source on the worker that will run it.
Which machine compiles matters: a node importing torch is fine on the
GPU box and a ``ModuleNotFoundError`` on the engine, so checking it
here would fail a node that is perfectly correct. When nothing is
attached there is nothing to check against, and ``None`` says so — the
node is not broken, it is waiting.
"""
worker = self.pick(label)
if worker is None:
return None
digest = hashlib.md5(f"{flow}.{node}:{source}".encode()).hexdigest()
if digest in worker.compiled:
return None
try:
response = worker.request(
{
"op": "compile",
"call_id": f"compile:{flow}.{node}",
"flow": flow,
"node": node,
"source": source,
},
timeout=timeout,
)
except RemoteError as exc:
return f"{type(exc).__name__}: {exc}"
if response.get("ok"):
worker.compiled.add(digest)
return None
error = response.get("error") or {}
return str(error.get("short") or "The node could not be loaded.")
def proxy(
self,
label: str,
flow: str,
node: str,
source: str,
node_id: str,
timeout: float,
run_id: str = "",
on_event: Callable[[dict[str, Any]], None] | None = None,
fallback: Callable[..., Any] | None = None,
env: dict[str, str] | None = None,
) -> Callable[..., Any]:
"""What a node with a device runs instead of its own function.
``fallback`` is the local pool's proxy, used when the node only prefers
the label rather than requiring it.
"""
def call(**kwargs: Any) -> Any:
if fallback is not None and self.pick(label) is None:
return fallback(**kwargs)
return self.run(
label,
flow,
node,
source,
kwargs,
node_id,
timeout,
run_id=run_id,
on_event=on_event,
env=env,
)
return call
def cancel_run(self, run_id: str) -> int:
"""Kill whatever this run has executing on any attached worker."""
stopped = 0
for worker in self.workers():
for call in worker.calls_of(run_id):
worker.cancel(call)
stopped += 1
return stopped