Source code for distributed.core

from __future__ import annotations

import asyncio
import inspect
import logging
import sys
import threading
import traceback
import types
import uuid
import warnings
import weakref
from collections import defaultdict, deque
from collections.abc import Container, Coroutine
from contextlib import suppress
from enum import Enum
from functools import partial
from typing import TYPE_CHECKING, Any, Callable, ClassVar, TypedDict, TypeVar, final

import tblib
from tlz import merge
from tornado.ioloop import IOLoop, PeriodicCallback

import dask
from dask.utils import parse_timedelta

from distributed import profile, protocol
from distributed.comm import (
    Comm,
    CommClosedError,
    connect,
    get_address_host_port,
    listen,
    normalize_address,
    unparse_host_port,
)
from distributed.metrics import time
from distributed.system_monitor import SystemMonitor
from distributed.utils import (
    NoOpAwaitable,
    get_traceback,
    has_keyword,
    iscoroutinefunction,
    recursive_to_dict,
    truncate_exception,
)

if TYPE_CHECKING:
    from typing_extensions import ParamSpec

    P = ParamSpec("P")
    R = TypeVar("R")
    T = TypeVar("T")
    Coro = Coroutine[Any, Any, T]


class Status(Enum):
    """
    This Enum contains the various states a cluster, worker, scheduler and nanny can be
    in. Some of the status can only be observed in one of cluster, nanny, scheduler or
    worker but we put them in the same Enum as they are compared with each
    other.
    """

    undefined = "undefined"
    created = "created"
    init = "init"
    starting = "starting"
    running = "running"
    paused = "paused"
    stopping = "stopping"
    stopped = "stopped"
    closing = "closing"
    closing_gracefully = "closing_gracefully"
    closed = "closed"
    failed = "failed"
    dont_reply = "dont_reply"


Status.lookup = {s.name: s for s in Status}  # type: ignore


class RPCClosed(IOError):
    pass


logger = logging.getLogger(__name__)


def raise_later(exc):
    def _raise(*args, **kwargs):
        raise exc

    return _raise


tick_maximum_delay = parse_timedelta(
    dask.config.get("distributed.admin.tick.limit"), default="ms"
)

LOG_PDB = dask.config.get("distributed.admin.pdb-on-err")


def _expects_comm(func: Callable) -> bool:
    sig = inspect.signature(func)
    params = list(sig.parameters)
    if params and params[0] == "comm":
        return True
    if params and params[0] == "stream":
        warnings.warn(
            "Calling the first arugment of a RPC handler `stream` is "
            "deprecated. Defining this argument is optional. Either remove the "
            f"arugment or rename it to `comm` in {func}.",
            FutureWarning,
        )
        return True
    return False


class _LoopBoundMixin:
    """Backport of the private asyncio.mixins._LoopBoundMixin from 3.11"""

    _global_lock = threading.Lock()

    _loop = None

    def _get_loop(self):
        loop = asyncio.get_running_loop()

        if self._loop is None:
            with self._global_lock:
                if self._loop is None:
                    self._loop = loop
        if loop is not self._loop:
            raise RuntimeError(f"{self!r} is bound to a different event loop")
        return loop


class AsyncTaskGroupClosedError(RuntimeError):
    pass


def _delayed(corofunc: Callable[P, Coro[T]], delay: float) -> Callable[P, Coro[T]]:
    """Decorator to delay the evaluation of a coroutine function by the given delay in seconds."""

    async def wrapper(*args: P.args, **kwargs: P.kwargs) -> T:
        await asyncio.sleep(delay)
        return await corofunc(*args, **kwargs)

    return wrapper


class AsyncTaskGroup(_LoopBoundMixin):
    """Collection tracking all currently running asynchronous tasks within a group"""

    #: If True, the group is closed and does not allow adding new tasks.
    closed: bool

    def __init__(self) -> None:
        self.closed = False
        self._ongoing_tasks: set[asyncio.Task[None]] = set()

    def call_soon(
        self, afunc: Callable[P, Coro[None]], /, *args: P.args, **kwargs: P.kwargs
    ) -> None:
        """Schedule a coroutine function to be executed as an `asyncio.Task`.

        The coroutine function `afunc` is scheduled with `args` arguments and `kwargs` keyword arguments
        as an `asyncio.Task`.

        Parameters
        ----------
        afunc
            Coroutine function to schedule.
        *args
            Arguments to be passed to `afunc`.
        **kwargs
            Keyword arguments to be passed to `afunc`

        Returns
        -------
            None

        Raises
        ------
        AsyncTaskGroupClosedError
            If the task group is closed.
        """
        if self.closed:  # Avoid creating a coroutine
            raise AsyncTaskGroupClosedError(
                "Cannot schedule a new coroutine function as the group is already closed."
            )
        task = self._get_loop().create_task(afunc(*args, **kwargs))
        task.add_done_callback(self._ongoing_tasks.remove)
        self._ongoing_tasks.add(task)
        return None

    def call_later(
        self,
        delay: float,
        afunc: Callable[P, Coro[None]],
        /,
        *args: P.args,
        **kwargs: P.kwargs,
    ) -> None:
        """Schedule a coroutine function to be executed after `delay` seconds as an `asyncio.Task`.

        The coroutine function `afunc` is scheduled with `args` arguments and `kwargs` keyword arguments
        as an `asyncio.Task` that is executed after `delay` seconds.

        Parameters
        ----------
        delay
            Delay in seconds.
        afunc
            Coroutine function to schedule.
        *args
            Arguments to be passed to `afunc`.
        **kwargs
            Keyword arguments to be passed to `afunc`

        Returns
        -------
            The None

        Raises
        ------
        AsyncTaskGroupClosedError
            If the task group is closed.
        """
        self.call_soon(_delayed(afunc, delay), *args, **kwargs)

    def close(self) -> None:
        """Closes the task group so that no new tasks can be scheduled.

        Existing tasks continue to run.
        """
        self.closed = True

    async def stop(self) -> None:
        """Close the group and stop all currently running tasks.

        Closes the task group and cancels all tasks. All tasks are cancelled
        an additional time for each time this task is cancelled.
        """
        self.close()

        current_task = asyncio.current_task(self._get_loop())
        err = None
        while tasks_to_stop := (self._ongoing_tasks - {current_task}):
            for task in tasks_to_stop:
                task.cancel()
            try:
                await asyncio.wait(tasks_to_stop)
            except asyncio.CancelledError as e:
                err = e

        if err is not None:
            raise err

    def __len__(self):
        return len(self._ongoing_tasks)


[docs]class Server: """Dask Distributed Server Superclass for endpoints in a distributed cluster, such as Worker and Scheduler objects. **Handlers** Servers define operations with a ``handlers`` dict mapping operation names to functions. The first argument of a handler function will be a ``Comm`` for the communication established with the client. Other arguments will receive inputs from the keys of the incoming message which will always be a dictionary. >>> def pingpong(comm): ... return b'pong' >>> def add(comm, x, y): ... return x + y >>> handlers = {'ping': pingpong, 'add': add} >>> server = Server(handlers) # doctest: +SKIP >>> server.listen('tcp://0.0.0.0:8000') # doctest: +SKIP **Message Format** The server expects messages to be dictionaries with a special key, `'op'` that corresponds to the name of the operation, and other key-value pairs as required by the function. So in the example above the following would be good messages. * ``{'op': 'ping'}`` * ``{'op': 'add', 'x': 10, 'y': 20}`` """ default_ip = "" default_port = 0 def __init__( self, handlers, blocked_handlers=None, stream_handlers=None, connection_limit=512, deserialize=True, serializers=None, deserializers=None, connection_args=None, timeout=None, io_loop=None, ): if io_loop is not None: warnings.warn( "The io_loop kwarg to Server is ignored and will be deprecated", DeprecationWarning, stacklevel=2, ) self._status = Status.init self.handlers = { "identity": self.identity, "echo": self.echo, "connection_stream": self.handle_stream, "dump_state": self._to_dict, } self.handlers.update(handlers) if blocked_handlers is None: blocked_handlers = dask.config.get( "distributed.%s.blocked-handlers" % type(self).__name__.lower(), [] ) self.blocked_handlers = blocked_handlers self.stream_handlers = {} self.stream_handlers.update(stream_handlers or {}) self.id = type(self).__name__ + "-" + str(uuid.uuid4()) self._address = None self._listen_address = None self._port = None self._host = None self._comms = {} self.deserialize = deserialize self.monitor = SystemMonitor() self.counters = None self.digests = None self._ongoing_background_tasks = AsyncTaskGroup() self._event_finished = asyncio.Event() self.listeners = [] self.io_loop = self.loop = IOLoop.current() if not hasattr(self.io_loop, "profile"): if dask.config.get("distributed.worker.profile.enabled"): ref = weakref.ref(self.io_loop) def stop() -> bool: loop = ref() return loop is None or loop.asyncio_loop.is_closed() self.io_loop.profile = profile.watch( omit=("profile.py", "selectors.py"), interval=dask.config.get("distributed.worker.profile.interval"), cycle=dask.config.get("distributed.worker.profile.cycle"), stop=stop, ) else: self.io_loop.profile = deque() # Statistics counters for various events with suppress(ImportError): from distributed.counter import Digest self.digests = defaultdict(partial(Digest, loop=self.io_loop)) from distributed.counter import Counter self.counters = defaultdict(partial(Counter, loop=self.io_loop)) self.periodic_callbacks = {} pc = PeriodicCallback( self.monitor.update, parse_timedelta( dask.config.get("distributed.admin.system-monitor.interval") ) * 1000, ) self.periodic_callbacks["monitor"] = pc self._last_tick = time() self._tick_counter = 0 self._tick_count = 0 self._tick_count_last = time() self._tick_interval = parse_timedelta( dask.config.get("distributed.admin.tick.interval"), default="ms" ) self._tick_interval_observed = self._tick_interval self.periodic_callbacks["tick"] = PeriodicCallback( self._measure_tick, self._tick_interval * 1000 ) self.periodic_callbacks["ticks"] = PeriodicCallback( self._cycle_ticks, parse_timedelta(dask.config.get("distributed.admin.tick.cycle")) * 1000, ) self.thread_id = 0 def set_thread_ident(): self.thread_id = threading.get_ident() self.io_loop.add_callback(set_thread_ident) self._startup_lock = asyncio.Lock() self.__startup_exc: Exception | None = None self.rpc = ConnectionPool( limit=connection_limit, deserialize=deserialize, serializers=serializers, deserializers=deserializers, connection_args=connection_args, timeout=timeout, server=self, ) self.__stopped = False @property def status(self) -> Status: try: return self._status except AttributeError: return Status.undefined @status.setter def status(self, value: Status) -> None: if not isinstance(value, Status): raise TypeError(f"Expected Status; got {value!r}") self._status = value async def finished(self): """Wait until the server has finished""" await self._event_finished.wait() def __await__(self): return self.start().__await__() async def start_unsafe(self): """Attempt to start the server. This is not idempotent and not protected against concurrent startup attempts. This is intended to be overwritten or called by subclasses. For a safe startup, please use ``Server.start`` instead. If ``death_timeout`` is configured, we will require this coroutine to finish before this timeout is reached. If the timeout is reached we will close the instance and raise an ``asyncio.TimeoutError`` """ await self.rpc.start() return self @final async def start(self): async with self._startup_lock: if self.status == Status.failed: assert self.__startup_exc is not None raise self.__startup_exc elif self.status != Status.init: return self timeout = getattr(self, "death_timeout", None) async def _close_on_failure(exc: Exception) -> None: await self.close() self.status = Status.failed self.__startup_exc = exc try: await asyncio.wait_for(self.start_unsafe(), timeout=timeout) except asyncio.TimeoutError as exc: await _close_on_failure(exc) raise asyncio.TimeoutError( f"{type(self).__name__} start timed out after {timeout}s." ) from exc except Exception as exc: await _close_on_failure(exc) raise RuntimeError(f"{type(self).__name__} failed to start.") from exc self.status = Status.running return self async def __aenter__(self): await self return self async def __aexit__(self, exc_type, exc_value, traceback): await self.close() def start_periodic_callbacks(self): """Start Periodic Callbacks consistently This starts all PeriodicCallbacks stored in self.periodic_callbacks if they are not yet running. It does this safely by checking that it is using the correct event loop. """ if self.io_loop.asyncio_loop is not asyncio.get_running_loop(): raise RuntimeError(f"{self!r} is bound to a different event loop") self._last_tick = time() for pc in self.periodic_callbacks.values(): if not pc.is_running(): pc.start() def stop(self): if self.__stopped: return self.__stopped = True _stops = set() for listener in self.listeners: future = listener.stop() if inspect.isawaitable(future): _stops.add(future) if _stops: async def background_stops(): await asyncio.gather(*_stops) self._ongoing_background_tasks.call_soon(background_stops) @property def listener(self): if self.listeners: return self.listeners[0] else: return None def _measure_tick(self): now = time() diff = now - self._last_tick self._last_tick = now self._tick_counter += 1 if diff > tick_maximum_delay: logger.info( "Event loop was unresponsive in %s for %.2fs. " "This is often caused by long-running GIL-holding " "functions or moving large chunks of data. " "This can cause timeouts and instability.", type(self).__name__, diff, ) if self.digests is not None: self.digests["tick-duration"].add(diff) def _cycle_ticks(self): if not self._tick_counter: return last, self._tick_count_last = self._tick_count_last, time() count, self._tick_counter = self._tick_counter, 0 self._tick_interval_observed = (time() - last) / (count or 1) @property def address(self) -> str: """ The address this Server can be contacted on. If the server is not up, yet, this raises a ValueError. """ if not self._address: if self.listener is None: raise ValueError("cannot get address of non-running Server") self._address = self.listener.contact_address return self._address @property def address_safe(self) -> str: """ The address this Server can be contacted on. If the server is not up, yet, this returns a ``"not-running"``. """ try: return self.address except ValueError: return "not-running" @property def listen_address(self): """ The address this Server is listening on. This may be a wildcard address such as `tcp://0.0.0.0:1234`. """ if not self._listen_address: if self.listener is None: raise ValueError("cannot get listen address of non-running Server") self._listen_address = self.listener.listen_address return self._listen_address @property def host(self): """ The host this Server is running on. This will raise ValueError if the Server is listening on a non-IP based protocol. """ if not self._host: self._host, self._port = get_address_host_port(self.address) return self._host @property def port(self): """ The port number this Server is listening on. This will raise ValueError if the Server is listening on a non-IP based protocol. """ if not self._port: self._host, self._port = get_address_host_port(self.address) return self._port def identity(self) -> dict[str, str]: return {"type": type(self).__name__, "id": self.id} def _to_dict(self, *, exclude: Container[str] = ()) -> dict: """Dictionary representation for debugging purposes. Not type stable and not intended for roundtrips. See also -------- Server.identity Client.dump_cluster_state distributed.utils.recursive_to_dict """ info = self.identity() extra = { "address": self.address, "status": self.status.name, "thread_id": self.thread_id, } info.update(extra) info = {k: v for k, v in info.items() if k not in exclude} return recursive_to_dict(info, exclude=exclude) def echo(self, data=None): return data async def listen(self, port_or_addr=None, allow_offload=True, **kwargs): if port_or_addr is None: port_or_addr = self.default_port if isinstance(port_or_addr, int): addr = unparse_host_port(self.default_ip, port_or_addr) elif isinstance(port_or_addr, tuple): addr = unparse_host_port(*port_or_addr) else: addr = port_or_addr assert isinstance(addr, str) listener = await listen( addr, self.handle_comm, deserialize=self.deserialize, allow_offload=allow_offload, **kwargs, ) self.listeners.append(listener) def handle_comm(self, comm): """Start a background task that dispatches new communications to coroutine-handlers""" try: self._ongoing_background_tasks.call_soon(self._handle_comm, comm) except AsyncTaskGroupClosedError: comm.abort() return NoOpAwaitable() async def _handle_comm(self, comm): """Dispatch new communications to coroutine-handlers Handlers is a dictionary mapping operation names to functions or coroutines. {'get_data': get_data, 'ping': pingpong} Coroutines should expect a single Comm object. """ if self.__stopped: comm.abort() return address = comm.peer_address op = None logger.debug("Connection from %r to %s", address, type(self).__name__) self._comms[comm] = op await self try: while not self.__stopped: try: msg = await comm.read() logger.debug("Message from %r: %s", address, msg) except OSError as e: if not sys.is_finalizing(): logger.debug( "Lost connection to %r while reading message: %s." " Last operation: %s", address, e, op, ) break except Exception as e: logger.exception("Exception while reading from %s", address) if comm.closed(): raise else: await comm.write(error_message(e, status="uncaught-error")) continue if not isinstance(msg, dict): raise TypeError( "Bad message type. Expected dict, got\n " + str(msg) ) try: op = msg.pop("op") except KeyError as e: raise ValueError( "Received unexpected message without 'op' key: " + str(msg) ) from e if self.counters is not None: self.counters["op"].add(op) self._comms[comm] = op serializers = msg.pop("serializers", None) close_desired = msg.pop("close", False) reply = msg.pop("reply", True) if op == "close": if reply: await comm.write("OK") break result = None try: if op in self.blocked_handlers: _msg = ( "The '{op}' handler has been explicitly disallowed " "in {obj}, possibly due to security concerns." ) exc = ValueError(_msg.format(op=op, obj=type(self).__name__)) handler = raise_later(exc) else: handler = self.handlers[op] except KeyError: logger.warning( "No handler %s found in %s", op, type(self).__name__, exc_info=True, ) else: if serializers is not None and has_keyword(handler, "serializers"): msg["serializers"] = serializers # add back in logger.debug("Calling into handler %s", handler.__name__) try: if _expects_comm(handler): result = handler(comm, **msg) else: result = handler(**msg) if inspect.iscoroutine(result): result = await result elif inspect.isawaitable(result): raise RuntimeError( f"Comm handler returned unknown awaitable. Expected coroutine, instead got {type(result)}" ) except CommClosedError: if self.status == Status.running: logger.info("Lost connection to %r", address, exc_info=True) break except Exception as e: logger.exception("Exception while handling op %s", op) if comm.closed(): raise else: result = error_message(e, status="uncaught-error") if reply and result != Status.dont_reply: try: await comm.write(result, serializers=serializers) except (OSError, TypeError) as e: logger.debug( "Lost connection to %r while sending result for op %r: %s", address, op, e, ) break self._comms[comm] = None msg = result = None if close_desired: await comm.close() if comm.closed(): break finally: del self._comms[comm] if not sys.is_finalizing() and not comm.closed(): try: comm.abort() except Exception as e: logger.error( "Failed while closing connection to %r: %s", address, e ) async def handle_stream(self, comm, extra=None): extra = extra or {} logger.info("Starting established connection") closed = False try: while not closed: msgs = await comm.read() if not isinstance(msgs, (tuple, list)): msgs = (msgs,) if not comm.closed(): for msg in msgs: if msg == "OK": # from close break op = msg.pop("op") if op: if op == "close-stream": closed = True break handler = self.stream_handlers[op] if iscoroutinefunction(handler): self._ongoing_background_tasks.call_soon( handler, **merge(extra, msg) ) await asyncio.sleep(0) else: handler(**merge(extra, msg)) else: logger.error("odd message %s", msg) await asyncio.sleep(0) except OSError: pass except Exception as e: logger.exception(e) if LOG_PDB: import pdb pdb.set_trace() raise finally: await comm.close() assert comm.closed() async def close(self, timeout=None): try: for pc in self.periodic_callbacks.values(): pc.stop() if not self.__stopped: self.__stopped = True _stops = set() for listener in self.listeners: future = listener.stop() if inspect.isawaitable(future): warnings.warn( f"{type(listener)} is using an asynchronous `stop` method. " "Support for asynchronous `Listener.stop` will be removed in a future version", PendingDeprecationWarning, ) _stops.add(future) if _stops: await asyncio.gather(*_stops) # TODO: Deal with exceptions await self._ongoing_background_tasks.stop() await self.rpc.close() await asyncio.gather(*[comm.close() for comm in list(self._comms)]) finally: self._event_finished.set()
def pingpong(comm): return b"pong" async def send_recv( # type: ignore[no-untyped-def] comm: Comm, *, reply: bool = True, serializers=None, deserializers=None, **kwargs, ): """Send and recv with a Comm. Keyword arguments turn into the message response = await send_recv(comm, op='ping', reply=True) """ msg = kwargs msg["reply"] = reply please_close = kwargs.get("close", False) force_close = False if deserializers is None: deserializers = serializers if deserializers is not None: msg["serializers"] = deserializers try: await comm.write(msg, serializers=serializers, on_error="raise") if reply: response = await comm.read(deserializers=deserializers) else: response = None except (asyncio.TimeoutError, OSError): # On communication errors, we should simply close the communication # Note that OSError includes CommClosedError and socket timeouts force_close = True raise except asyncio.CancelledError: # Do not reuse the comm to prevent the next call of send_recv from receiving # data from this call and/or accidentally putting multiple waiters on read(). # Note that this relies on all Comm implementations to allow a write() in the # middle of a read(). please_close = True raise finally: if force_close: comm.abort() elif please_close: await comm.close() if isinstance(response, dict) and response.get("status") == "uncaught-error": if comm.deserialize: _, exc, tb = clean_exception(**response) assert exc raise exc.with_traceback(tb) else: raise Exception(response["exception_text"]) return response def addr_from_args(addr=None, ip=None, port=None): if addr is None: addr = (ip, port) else: assert ip is None and port is None if isinstance(addr, tuple): addr = unparse_host_port(*addr) return normalize_address(addr)
[docs]class rpc: """Conveniently interact with a remote server >>> remote = rpc(address) # doctest: +SKIP >>> response = await remote.add(x=10, y=20) # doctest: +SKIP One rpc object can be reused for several interactions. Additionally, this object creates and destroys many comms as necessary and so is safe to use in multiple overlapping communications. When done, close comms explicitly. >>> remote.close_comms() # doctest: +SKIP """ active: ClassVar[weakref.WeakSet[rpc]] = weakref.WeakSet() comms = () address = None def __init__( self, arg=None, comm=None, deserialize=True, timeout=None, connection_args=None, serializers=None, deserializers=None, ): self.comms = {} self.address = coerce_to_address(arg) self.timeout = timeout self.status = Status.running self.deserialize = deserialize self.serializers = serializers self.deserializers = deserializers if deserializers is not None else serializers self.connection_args = connection_args or {} self._created = weakref.WeakSet() rpc.active.add(self) async def live_comm(self): """Get an open communication Some comms to the ip/port target may be in current use by other coroutines. We track this with the `comms` dict :: {comm: True/False if open and ready for use} This function produces an open communication, either by taking one that we've already made or making a new one if they are all taken. This also removes comms that have been closed. When the caller is done with the stream they should set self.comms[comm] = True As is done in __getattr__ below. """ if self.status == Status.closed: raise RPCClosed("RPC Closed") to_clear = set() open = False for comm, open in self.comms.items(): if comm.closed(): to_clear.add(comm) if open: break for s in to_clear: del self.comms[s] if not open or comm.closed(): comm = await connect( self.address, self.timeout, deserialize=self.deserialize, **self.connection_args, ) comm.name = "rpc" self.comms[comm] = False # mark as taken return comm def close_comms(self): async def _close_comm(comm): # Make sure we tell the peer to close try: if not comm.closed(): await comm.write({"op": "close", "reply": False}) await comm.close() except OSError: comm.abort() tasks = [] for comm in list(self.comms): if comm and not comm.closed(): task = asyncio.ensure_future(_close_comm(comm)) tasks.append(task) for comm in list(self._created): if comm and not comm.closed(): task = asyncio.ensure_future(_close_comm(comm)) tasks.append(task) self.comms.clear() return tasks def __getattr__(self, key): async def send_recv_from_rpc(**kwargs): if self.serializers is not None and kwargs.get("serializers") is None: kwargs["serializers"] = self.serializers if self.deserializers is not None and kwargs.get("deserializers") is None: kwargs["deserializers"] = self.deserializers comm = None try: comm = await self.live_comm() comm.name = "rpc." + key result = await send_recv(comm=comm, op=key, **kwargs) except (RPCClosed, CommClosedError) as e: if comm: raise type(e)( f"Exception while trying to call remote method {key!r} before comm was established." ) from e else: raise type(e)( f"Exception while trying to call remote method {key!r} using comm {comm!r}." ) from e self.comms[comm] = True # mark as open return result return send_recv_from_rpc async def close_rpc(self): if self.status != Status.closed: rpc.active.discard(self) self.status = Status.closed return await asyncio.gather(*self.close_comms()) def __enter__(self): warnings.warn( "the rpc synchronous context manager is deprecated", DeprecationWarning, stacklevel=2, ) return self def __exit__(self, exc_type, exc_value, traceback): asyncio.ensure_future(self.close_rpc()) async def __aenter__(self): return self async def __aexit__(self, exc_type, exc_value, traceback): await self.close_rpc() def __del__(self): if self.status != Status.closed: rpc.active.discard(self) self.status = Status.closed still_open = [comm for comm in self.comms if not comm.closed()] if still_open: logger.warning( "rpc object %s deleted with %d open comms", self, len(still_open) ) for comm in still_open: comm.abort() def __repr__(self): return "<rpc to %r, %d comms>" % (self.address, len(self.comms))
class PooledRPCCall: """The result of ConnectionPool()('host:port') See Also: ConnectionPool """ def __init__(self, addr, pool, serializers=None, deserializers=None): self.addr = addr self.pool = pool self.serializers = serializers self.deserializers = deserializers if deserializers is not None else serializers @property def address(self): return self.addr def __getattr__(self, key): async def send_recv_from_rpc(**kwargs): if self.serializers is not None and kwargs.get("serializers") is None: kwargs["serializers"] = self.serializers if self.deserializers is not None and kwargs.get("deserializers") is None: kwargs["deserializers"] = self.deserializers comm = await self.pool.connect(self.addr) prev_name, comm.name = comm.name, "ConnectionPool." + key try: return await send_recv(comm=comm, op=key, **kwargs) finally: self.pool.reuse(self.addr, comm) comm.name = prev_name return send_recv_from_rpc async def close_rpc(self): pass # For compatibility with rpc() def __enter__(self): warnings.warn( "the rpc synchronous context manager is deprecated", DeprecationWarning, stacklevel=2, ) return self def __exit__(self, exc_type, exc_value, traceback): pass async def __aenter__(self): return self async def __aexit__(self, *args): pass def __repr__(self): return f"<pooled rpc to {self.addr!r}>" class ConnectionPool: """A maximum sized pool of Comm objects. This provides a connect method that mirrors the normal distributed.connect method, but provides connection sharing and tracks connection limits. This object provides an ``rpc`` like interface:: >>> rpc = ConnectionPool(limit=512) >>> scheduler = rpc('127.0.0.1:8786') >>> workers = [rpc(address) for address in ...] >>> info = await scheduler.identity() It creates enough comms to satisfy concurrent connections to any particular address:: >>> a, b = await asyncio.gather(scheduler.who_has(), scheduler.has_what()) It reuses existing comms so that we don't have to continuously reconnect. It also maintains a comm limit to avoid "too many open file handle" issues. Whenever this maximum is reached we clear out all idling comms. If that doesn't do the trick then we wait until one of the occupied comms closes. Parameters ---------- limit: int The number of open comms to maintain at once deserialize: bool Whether or not to deserialize data by default or pass it through """ _instances: ClassVar[weakref.WeakSet[ConnectionPool]] = weakref.WeakSet() def __init__( self, limit=512, deserialize=True, serializers=None, allow_offload=True, deserializers=None, connection_args=None, timeout=None, server=None, ): self.limit = limit # Max number of open comms # Invariant: len(available) == open - active self.available = defaultdict(set) # Invariant: len(occupied) == active self.occupied = defaultdict(set) self.allow_offload = allow_offload self.deserialize = deserialize self.serializers = serializers self.deserializers = deserializers if deserializers is not None else serializers self.connection_args = connection_args or {} self.timeout = timeout self.server = weakref.ref(server) if server else None self._created = weakref.WeakSet() self._instances.add(self) # _n_connecting and _connecting have subtle different semantics. The set # _connecting contains futures actively trying to establish a connection # while the _n_connecting also accounts for connection attempts which # are waiting due to the connection limit self._connecting = set() self._pending_count = 0 self._connecting_count = 0 self.status = Status.init def _validate(self): """ Validate important invariants of this class Used only for testing / debugging """ assert self.semaphore._value == self.limit - self.open - self._n_connecting @property def active(self): return sum(map(len, self.occupied.values())) @property def open(self): return self.active + sum(map(len, self.available.values())) def __repr__(self): return "<ConnectionPool: open=%d, active=%d, connecting=%d>" % ( self.open, self.active, len(self._connecting), ) def __call__(self, addr=None, ip=None, port=None): """Cached rpc objects""" addr = addr_from_args(addr=addr, ip=ip, port=port) return PooledRPCCall( addr, self, serializers=self.serializers, deserializers=self.deserializers ) def __await__(self): async def _(): await self.start() return self return _().__await__() async def start(self): # Invariant: semaphore._value == limit - open - _n_connecting self.semaphore = asyncio.Semaphore(self.limit) self.status = Status.running @property def _n_connecting(self) -> int: return self._connecting_count async def _connect(self, addr, timeout=None): self._pending_count += 1 try: await self.semaphore.acquire() try: self._connecting_count += 1 comm = await connect( addr, timeout=timeout or self.timeout, deserialize=self.deserialize, **self.connection_args, ) comm.name = "ConnectionPool" comm._pool = weakref.ref(self) comm.allow_offload = self.allow_offload self._created.add(comm) self.occupied[addr].add(comm) return comm except BaseException: self.semaphore.release() raise finally: self._connecting_count -= 1 except asyncio.CancelledError: raise CommClosedError("ConnectionPool closing.") finally: self._pending_count -= 1 async def connect(self, addr, timeout=None): """ Get a Comm to the given address. For internal use. """ available = self.available[addr] occupied = self.occupied[addr] while available: comm = available.pop() if comm.closed(): self.semaphore.release() else: occupied.add(comm) return comm if self.semaphore.locked(): self.collect() # This construction is there to ensure that cancellation requests from # the outside can be distinguished from cancellations of our own. # Once the CommPool closes, we'll cancel the connect_attempt which will # raise an OSError # If the ``connect`` is cancelled from the outside, the Event.wait will # be cancelled instead which we'll reraise as a CancelledError and allow # it to propagate connect_attempt = asyncio.create_task(self._connect(addr, timeout)) done = asyncio.Event() self._connecting.add(connect_attempt) connect_attempt.add_done_callback(lambda _: done.set()) connect_attempt.add_done_callback(self._connecting.discard) try: await done.wait() except asyncio.CancelledError: # This is an outside cancel attempt connect_attempt.cancel() try: await connect_attempt except CommClosedError: pass raise return await connect_attempt def reuse(self, addr, comm): """ Reuse an open communication to the given address. For internal use. """ # if the pool is asked to re-use a comm it does not know about, ignore # this comm: just close it. if comm not in self.occupied[addr]: IOLoop.current().add_callback(comm.close) else: self.occupied[addr].remove(comm) if comm.closed(): # Either the user passed the close=True parameter to send_recv, or # the RPC call raised OSError or CancelledError self.semaphore.release() else: self.available[addr].add(comm) if self.semaphore.locked() and self._pending_count: self.collect() def collect(self): """ Collect open but unused communications, to allow opening other ones. """ logger.info( "Collecting unused comms. open: %d, active: %d, connecting: %d", self.open, self.active, len(self._connecting), ) for comms in self.available.values(): for comm in comms: IOLoop.current().add_callback(comm.close) self.semaphore.release() comms.clear() def remove(self, addr): """ Remove all Comms to a given address. """ logger.info("Removing comms to %s", addr) if addr in self.available: comms = self.available.pop(addr) for comm in comms: IOLoop.current().add_callback(comm.close) self.semaphore.release() if addr in self.occupied: comms = self.occupied.pop(addr) for comm in comms: IOLoop.current().add_callback(comm.close) self.semaphore.release() async def close(self): """ Close all communications """ self.status = Status.closed for conn_fut in self._connecting: conn_fut.cancel() for d in [self.available, self.occupied]: comms = set() while d: comms.update(d.popitem()[1]) await asyncio.gather( *(comm.close() for comm in comms), return_exceptions=True ) for _ in comms: self.semaphore.release() while self._connecting: await asyncio.sleep(0.005) def coerce_to_address(o): if isinstance(o, (list, tuple)): o = unparse_host_port(*o) return normalize_address(o) def collect_causes(e: BaseException) -> list[BaseException]: causes = [] while e.__cause__ is not None: causes.append(e.__cause__) e = e.__cause__ return causes class ErrorMessage(TypedDict): status: str exception: protocol.Serialize traceback: protocol.Serialize | None exception_text: str traceback_text: str def error_message(e: BaseException, status: str = "error") -> ErrorMessage: """Produce message to send back given an exception has occurred This does the following: 1. Gets the traceback 2. Truncates the exception and the traceback 3. Serializes the exception and traceback or 4. If they can't be serialized send string versions 5. Format a message and return See Also -------- clean_exception : deserialize and unpack message into exception/traceback """ MAX_ERROR_LEN = dask.config.get("distributed.admin.max-error-length") tblib.pickling_support.install(e, *collect_causes(e)) tb = get_traceback() tb_text = "".join(traceback.format_tb(tb)) e = truncate_exception(e, MAX_ERROR_LEN) try: e_bytes = protocol.pickle.dumps(e) protocol.pickle.loads(e_bytes) except Exception: e_bytes = protocol.pickle.dumps(Exception(repr(e))) e_serialized = protocol.to_serialize(e_bytes) try: tb_bytes = protocol.pickle.dumps(tb) protocol.pickle.loads(tb_bytes) except Exception: tb_bytes = protocol.pickle.dumps(tb_text) if len(tb_bytes) > MAX_ERROR_LEN: tb_serialized = None else: tb_serialized = protocol.to_serialize(tb_bytes) return { "status": status, "exception": e_serialized, "traceback": tb_serialized, "exception_text": repr(e), "traceback_text": tb_text, } def clean_exception( exception: BaseException | bytes | bytearray | str | None, traceback: types.TracebackType | bytes | str | None = None, **kwargs: Any, ) -> tuple[ type[BaseException | None], BaseException | None, types.TracebackType | None ]: """Reraise exception and traceback. Deserialize if necessary See Also -------- error_message : create and serialize errors into message """ if isinstance(exception, (bytes, bytearray)): try: exception = protocol.pickle.loads(exception) except Exception: exception = Exception(exception) elif isinstance(exception, str): exception = Exception(exception) if isinstance(traceback, bytes): try: traceback = protocol.pickle.loads(traceback) except (TypeError, AttributeError): traceback = None elif isinstance(traceback, str): traceback = None # happens if the traceback failed serializing assert isinstance(exception, BaseException) or exception is None assert isinstance(traceback, types.TracebackType) or traceback is None return type(exception), exception, traceback