Source code for distributed.core

from __future__ import print_function, division, absolute_import

from collections import defaultdict
from datetime import timedelta
import logging
import six
import socket
import struct
from time import time
import traceback
import uuid

from toolz import assoc, first

try:
    import cPickle as pickle
except ImportError:
    import pickle
import cloudpickle
from tornado import gen
from tornado.locks import Event
from tornado.tcpserver import TCPServer
from tornado.tcpclient import TCPClient
from tornado.ioloop import IOLoop
from tornado.iostream import IOStream, StreamClosedError

from .compatibility import PY3, unicode, WINDOWS
from .utils import get_traceback, truncate_exception, ignoring
from . import protocol


class RPCClosed(IOError):
    pass


logger = logging.getLogger(__name__)


def get_total_physical_memory():
    try:
        import psutil
        return psutil.virtual_memory().total / 2
    except ImportError:
        return 2e9


MAX_BUFFER_SIZE = get_total_physical_memory()


def handle_signal(sig, frame):
    IOLoop.instance().add_callback(IOLoop.instance().stop)


[docs]class Server(TCPServer): """ Distributed TCP Server Superclass for both Worker and Scheduler objects. Inherits from ``tornado.tcpserver.TCPServer``, adding a protocol for RPC. **Handlers** Servers define operations with a ``handlers`` dict mapping operation names to functions. The first argument of a handler function must be a stream for the connection to the client. Other arguments will receive inputs from the keys of the incoming message which will always be a dictionary. >>> def pingpong(stream): ... return b'pong' >>> def add(stream, x, y): ... return x + y >>> handlers = {'ping': pingpong, 'add': add} >>> server = Server(handlers) # doctest: +SKIP >>> server.listen(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_port = 0 def __init__(self, handlers, max_buffer_size=MAX_BUFFER_SIZE, connection_limit=512, deserialize=True, **kwargs): self.handlers = assoc(handlers, 'identity', self.identity) self.id = str(uuid.uuid1()) self._port = None self.rpc = ConnectionPool(limit=connection_limit, deserialize=deserialize) self.deserialize = deserialize super(Server, self).__init__(max_buffer_size=max_buffer_size, **kwargs) @property def port(self): if not self._port: try: self._port = first(self._sockets.values()).getsockname()[1] except StopIteration: raise OSError("Server has no port. Please call .listen first") return self._port def identity(self, stream): return {'type': type(self).__name__, 'id': self.id} def listen(self, port=None): if port is None: port = self.default_port while True: try: super(Server, self).listen(port) break except (socket.error, OSError): if port: raise else: logger.info('Randomly assigned port taken for %s. Retrying', type(self).__name__) @gen.coroutine def handle_stream(self, stream, address): """ Dispatch new connections 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 IOStream object. """ stream.set_nodelay(True) ip, port = address logger.info("Connection from %s:%d to %s", ip, port, type(self).__name__) try: while True: try: msg = yield read(stream, deserialize=self.deserialize) logger.debug("Message from %s:%d: %s", ip, port, msg) except StreamClosedError: logger.info("Lost connection: %s", str(address)) break except Exception as e: logger.exception(e) yield write(stream, error_message(e, status='uncaught-error')) continue if not isinstance(msg, dict): raise TypeError("Bad message type. Expected dict, got\n " + str(msg)) op = msg.pop('op') close = msg.pop('close', False) reply = msg.pop('reply', True) if op == 'close': if reply: yield write(stream, 'OK') break try: handler = self.handlers[op] except KeyError: result = "No handler found: %s" % op logger.warn(result, exc_info=True) else: logger.debug("Calling into handler %s", handler.__name__) try: result = yield gen.maybe_future(handler(stream, **msg)) except StreamClosedError as e: logger.info("%s", e) result = error_message(e, status='uncaught-error') except Exception as e: logger.exception(e) result = error_message(e, status='uncaught-error') if reply: try: yield write(stream, result) except StreamClosedError: logger.info("Lost connection: %s" % str(address)) break if close: break finally: try: stream.close() except Exception as e: logger.warn("Failed while closing writer", exc_info=True) logger.info("Close connection from %s:%d to %s", address[0], address[1], type(self).__name__)
@gen.coroutine
[docs]def read(stream, deserialize=True): """ Read a message from a stream """ if isinstance(stream, BatchedStream): msg = yield stream.recv() raise gen.Return(msg) else: n_frames = yield stream.read_bytes(8) n_frames = struct.unpack('Q', n_frames)[0] lengths = yield stream.read_bytes(8 * n_frames) lengths = struct.unpack('Q' * n_frames, lengths) frames = [] for length in lengths: if length: frame = yield stream.read_bytes(length) else: frame = b'' frames.append(frame) msg = protocol.loads(frames, deserialize=deserialize) raise gen.Return(msg)
@gen.coroutine
[docs]def write(stream, msg): """ Write a message to a stream """ if isinstance(stream, BatchedStream): stream.send(msg) else: try: frames = protocol.dumps(msg) except Exception as e: logger.info("Unserializable Message: %s", msg) logger.exception(e) raise futures = [] lengths = ([struct.pack('Q', len(frames))] + [struct.pack('Q', len(frame)) for frame in frames]) futures.append(stream.write(b''.join(lengths))) for frame in frames[:-1]: futures.append(stream.write(frame)) futures.append(stream.write(frames[-1])) while stream._write_buffer: try: yield gen.with_timeout(timedelta(seconds=0.01), futures[-1]) break except gen.TimeoutError: pass
def pingpong(stream): return b'pong' @gen.coroutine def connect(ip, port, timeout=3): client = TCPClient() start = time() while True: future = client.connect(ip, port, max_buffer_size=MAX_BUFFER_SIZE) try: stream = yield gen.with_timeout(timedelta(seconds=timeout), future) stream.set_nodelay(True) raise gen.Return(stream) except StreamClosedError: if time() - start < timeout: yield gen.sleep(0.01) logger.debug("sleeping on connect") else: raise except gen.TimeoutError: raise IOError("Timed out while connecting to %s:%d" % (ip, port)) @gen.coroutine def send_recv(stream=None, arg=None, ip=None, port=None, addr=None, reply=True, deserialize=True, **kwargs): """ Send and recv with a stream Keyword arguments turn into the message response = yield send_recv(stream, op='ping', reply=True) """ if arg: if isinstance(arg, (unicode, bytes)): addr = arg if isinstance(arg, tuple): ip, port = arg if addr: assert not ip and not port if PY3 and isinstance(addr, bytes): addr = addr.decode() ip, port = addr.rsplit(':', 1) port = int(port) if PY3 and isinstance(ip, bytes): ip = ip.decode() if stream is None: stream = yield connect(ip, port) msg = kwargs msg['reply'] = reply yield write(stream, msg) if reply: response = yield read(stream, deserialize=deserialize) if isinstance(response, dict) and response.get('status') == 'uncaught-error': six.reraise(*clean_exception(**response)) else: response = None if kwargs.get('close'): stream.close() raise gen.Return(response) def ip_port_from_args(arg=None, addr=None, ip=None, port=None): if arg: if isinstance(arg, (unicode, bytes)): addr = arg if isinstance(arg, tuple): ip, port = arg if addr: if PY3 and isinstance(addr, bytes): addr = addr.decode() assert not ip and not port ip, port = addr.rsplit(':', 1) port = int(port) if PY3 and isinstance(ip, bytes): ip = ip.decode() return ip, port
[docs]class rpc(object): """ Conveniently interact with a remote server Normally we construct messages as dictionaries and send them with read/write >>> stream = yield connect(ip, port) # doctest: +SKIP >>> msg = {'op': 'add', 'x': 10, 'y': 20} # doctest: +SKIP >>> yield write(stream, msg) # doctest: +SKIP >>> response = yield read(stream) # doctest: +SKIP To reduce verbosity we use an ``rpc`` object. >>> remote = rpc(ip=ip, port=port) # doctest: +SKIP >>> response = yield remote.add(x=10, y=20) # doctest: +SKIP One rpc object can be reused for several interactions. Additionally, this object creates and destroys many streams as necessary and so is safe to use in multiple overlapping communications. When done, close streams explicitly. >>> remote.close_streams() # doctest: +SKIP """ active = 0 def __init__(self, arg=None, stream=None, ip=None, port=None, addr=None, deserialize=True, timeout=3): ip, port = ip_port_from_args(arg=arg, addr=addr, ip=ip, port=port) self.streams = dict() self.ip = ip self.port = port self.timeout = timeout self.status = 'running' self.deserialize = deserialize rpc.active += 1 assert self.ip assert self.port @property def address(self): return '%s:%d' % (self.ip, self.port) @gen.coroutine def live_stream(self): """ Get an open stream Some streams to the ip/port target may be in current use by other coroutines. We track this with the `streams` dict :: {stream: True/False if open and ready for use} This function produces an open stream, either by taking one that we've already made or making a new one if they are all taken. This also removes streams that have been closed. When the caller is done with the stream they should set self.streams[stream] = True As is done in __getattr__ below. """ if self.status == 'closed': raise RPCClosed("RPC Closed") to_clear = set() open = False for stream, open in self.streams.items(): if stream.closed(): to_clear.add(stream) if open: break if not open or stream.closed(): stream = yield connect(self.ip, self.port, timeout=self.timeout) for s in to_clear: del self.streams[s] self.streams[stream] = False # mark as taken raise gen.Return(stream) def close_streams(self): for stream in self.streams: if stream and not stream.closed(): try: stream.close() except (OSError, IOError, StreamClosedError): pass self.streams.clear() def __getattr__(self, key): @gen.coroutine def send_recv_from_rpc(**kwargs): stream = yield self.live_stream() result = yield send_recv(stream=stream, op=key, deserialize=self.deserialize, **kwargs) self.streams[stream] = True # mark as open raise gen.Return(result) return send_recv_from_rpc def close_rpc(self): if self.status != 'closed': rpc.active -= 1 self.status = 'closed' self.close_streams() def __enter__(self): return self def __exit__(self, *args): self.close_rpc()
class RPCCall(object): """ The result of ConnectionPool()('host:port') See Also: ConnectionPool """ def __init__(self, ip, port, pool): self.ip = ip self.port = port self.pool = pool def __getattr__(self, key): @gen.coroutine def send_recv_from_rpc(**kwargs): stream = yield self.pool.connect(self.ip, self.port) try: result = yield send_recv(stream=stream, op=key, deserialize=self.pool.deserialize, **kwargs) finally: if not stream.closed(): self.pool.available[self.ip, self.port].add(stream) self.pool.occupied[self.ip, self.port].remove(stream) self.pool.active -= 1 raise gen.Return(result) return send_recv_from_rpc def close_rpc(self): pass class ConnectionPool(object): """ A maximum sized pool of Tornado IOStreams 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(ip=ip, port=port) for ip, port in ...] >>> info = yield scheduler.identity() It creates enough streams to satisfy concurrent connections to any particular address:: >>> a, b = yield [scheduler.who_has(), scheduler.has_what()] It reuses existing streams so that we don't have to continuously reconnect. It also maintains a stream limit to avoid "too many open file handle" issues. Whenever this maximum is reached we clear out all idling streams. If that doesn't do the trick then we wait until one of the occupied streams closes. Parameters ---------- limit: int The number of open streams to maintain at once deserialize: bool Whether or not to deserialize data by default or pass it through """ def __init__(self, limit=512, deserialize=True): self.open = 0 self.active = 0 self.limit = limit self.available = defaultdict(set) self.occupied = defaultdict(set) self.deserialize = deserialize self.event = Event() def __str__(self): return "<ConnectionPool: open=%d, active=%d>" % (self.open, self.active) __repr__ = __str__ def __call__(self, arg=None, ip=None, port=None, addr=None): """ Cached rpc objects """ ip, port = ip_port_from_args(arg=arg, addr=addr, ip=ip, port=port) return RPCCall(ip, port, self) @gen.coroutine def connect(self, ip, port, timeout=3): if self.available.get((ip, port)): stream = self.available[ip, port].pop() self.active += 1 self.occupied[ip, port].add(stream) raise gen.Return(stream) while self.open >= self.limit: self.event.clear() self.collect() yield self.event.wait() self.open += 1 stream = yield connect(ip=ip, port=port, timeout=timeout) stream.set_close_callback(lambda: self.on_close(ip, port, stream)) self.active += 1 self.occupied[ip, port].add(stream) if self.open >= self.limit: self.event.clear() raise gen.Return(stream) def on_close(self, ip, port, stream): self.open -= 1 if stream in self.available[ip, port]: self.available[ip, port].remove(stream) if stream in self.occupied[ip, port]: self.occupied[ip, port].remove(stream) self.active -= 1 if self.open <= self.limit: self.event.set() def collect(self): logger.info("Collecting unused streams. open: %d, active: %d", self.open, self.active) for streams in list(self.available.values()): for stream in streams: stream.close() def close(self): for streams in list(self.available.values()): for stream in streams: stream.close() for streams in list(self.occupied.values()): for stream in streams: stream.close() def coerce_to_address(o, out=str): if PY3 and isinstance(o, bytes): o = o.decode() if isinstance(o, (unicode, str)): ip, port = o.rsplit(':', 1) port = int(port) o = (ip, port) if isinstance(o, list): o = tuple(o) if isinstance(o, tuple) and isinstance(o[0], bytes): o = (o[0].decode(), o[1]) if out == str: o = '%s:%s' % o return o def coerce_to_rpc(o, **kwargs): if isinstance(o, (bytes, str, tuple, list)): ip, port = coerce_to_address(o, out=tuple) return rpc(ip=ip, port=int(port), **kwargs) elif isinstance(o, IOStream): return rpc(stream=o, **kwargs) elif isinstance(o, rpc): return o else: raise TypeError() def error_message(e, status='error'): """ 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 six.reraise: raise exception/traceback """ tb = get_traceback() e2 = truncate_exception(e, 1000) try: e3 = protocol.pickle.dumps(e2) protocol.pickle.loads(e3) except Exception: e3 = Exception(str(e2)) e3 = protocol.pickle.dumps(e3) try: tb2 = protocol.pickle.dumps(tb) except Exception: tb2 = ''.join(traceback.format_tb(tb)) tb2 = protocol.pickle.dumps(tb2) if len(tb2) > 10000: tb2 = None return {'status': status, 'exception': e3, 'traceback': tb2} def clean_exception(exception, traceback, **kwargs): """ Reraise exception and traceback. Deserialize if necessary See Also -------- error_message: create and serialize errors into message """ if isinstance(exception, bytes): exception = protocol.pickle.loads(exception) if isinstance(traceback, bytes): traceback = protocol.pickle.loads(traceback) if isinstance(traceback, str): traceback = None return type(exception), exception, traceback from .batched import BatchedStream