from __future__ import print_function, division, absolute_import
from collections import defaultdict, deque
from functools import partial
import logging
import six
import traceback
import uuid
import weakref
from six import string_types
from toolz import assoc
from tornado import gen
from tornado.ioloop import IOLoop
from tornado.locks import Event
from .comm import (connect, listen, CommClosedError,
normalize_address,
unparse_host_port, get_address_host_port)
from .config import config
from .metrics import time
from .system_monitor import SystemMonitor
from .utils import (get_traceback, truncate_exception, ignoring, shutting_down,
PeriodicCallback)
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()
[docs]class Server(object):
""" Distributed TCP 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, connection_limit=512, deserialize=True,
io_loop=None):
self.handlers = assoc(handlers, 'identity', self.identity)
self.id = type(self).__name__ + '-' + str(uuid.uuid4())
self._address = None
self._listen_address = None
self._port = None
self._comms = {}
self.deserialize = deserialize
self.monitor = SystemMonitor()
self.counters = None
self.digests = None
self.events = None
self.event_counts = None
self._ongoing_coroutines = weakref.WeakSet()
self.listener = None
self.io_loop = io_loop or IOLoop.current()
# Statistics counters for various events
with ignoring(ImportError):
from .counter import Digest
self.digests = defaultdict(partial(Digest, loop=self.io_loop))
from .counter import Counter
self.counters = defaultdict(partial(Counter, loop=self.io_loop))
self.events = defaultdict(lambda: deque(maxlen=10000))
self.event_counts = defaultdict(lambda: 0)
self.periodic_callbacks = dict()
pc = PeriodicCallback(self.monitor.update, 500)
self.periodic_callbacks['monitor'] = pc
self._last_tick = time()
pc = PeriodicCallback(self._measure_tick, config.get('tick-time', 20))
self.periodic_callbacks['tick'] = pc
self.__stopped = False
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 on the IOLoop.
"""
def start_pcs():
for pc in self.periodic_callbacks.values():
if not pc.is_running():
pc.start()
self.loop.add_callback(start_pcs)
def stop(self):
if not self.__stopped:
self.__stopped = True
if self.listener is not None:
# Delay closing the server socket until the next IO loop tick.
# Otherwise race conditions can appear if an event handler
# for an accept() call is already scheduled by the IO loop,
# raising EBADF.
# The demonstrator for this is Worker.terminate(), which
# closes the server socket in response to an incoming message.
# See https://github.com/tornadoweb/tornado/issues/2069
self.io_loop.add_callback(self.listener.stop)
def _measure_tick(self):
now = time()
diff = now - self._last_tick
self._last_tick = now
if diff > config.get('tick-maximum-delay', 1000) / 1000:
logger.warning("Event loop was unresponsive for %.2fs. "
"This is often caused by long-running GIL-holding "
"functions or moving large chunks of data. "
"This can cause timeouts and instability.",
diff)
if self.digests is not None:
self.digests['tick-duration'].add(diff)
def log_event(self, name, msg):
msg['time'] = time()
if isinstance(name, list):
for n in name:
self.events[n].append(msg)
self.event_counts[n] += 1
else:
self.events[name].append(msg)
self.event_counts[name] += 1
@property
def address(self):
"""
The address this Server can be contacted on.
"""
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 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 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._port = get_address_host_port(self.address)
return self._port
def identity(self, comm):
return {'type': type(self).__name__, 'id': self.id}
def listen(self, port_or_addr=None, listen_args=None):
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, string_types)
self.listener = listen(addr, self.handle_comm,
deserialize=self.deserialize,
connection_args=listen_args)
self.listener.start()
@gen.coroutine
def handle_comm(self, comm, shutting_down=shutting_down):
""" 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
try:
while True:
try:
msg = yield comm.read()
logger.debug("Message from %r: %s", address, msg)
except EnvironmentError as e:
if not shutting_down():
logger.debug("Lost connection to %r while reading message: %s."
" Last operation: %s",
address, e, op)
break
except Exception as e:
logger.exception(e)
yield 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))
op = msg.pop('op')
if self.counters is not None:
self.counters['op'].add(op)
self._comms[comm] = op
close_desired = msg.pop('close', False)
reply = msg.pop('reply', True)
if op == 'close':
if reply:
yield comm.write('OK')
break
try:
handler = self.handlers[op]
except KeyError:
result = "No handler found: %s" % op
logger.warning(result, exc_info=True)
else:
logger.debug("Calling into handler %s", handler.__name__)
try:
result = handler(comm, **msg)
if type(result) is gen.Future:
self._ongoing_coroutines.add(result)
result = yield result
except CommClosedError as e:
logger.warning("Lost connection to %r: %s", address, e)
break
except Exception as e:
logger.exception(e)
result = error_message(e, status='uncaught-error')
if reply and result != 'dont-reply':
try:
yield comm.write(result)
except EnvironmentError as e:
logger.debug("Lost connection to %r while sending result for op %r: %s",
address, op, e)
break
msg = result = None
if close_desired:
yield comm.close()
if comm.closed():
break
finally:
del self._comms[comm]
if not shutting_down() and not comm.closed():
try:
comm.abort()
except Exception as e:
logger.error("Failed while closing connection to %r: %s",
address, e)
@gen.coroutine
def close(self):
self.listener.stop()
for comm in self._comms:
comm.close()
for cb in self._ongoing_coroutines:
cb.cancel()
for i in range(10):
if all(cb.cancelled() for c in self._ongoing_coroutines):
break
else:
yield gen.sleep(0.01)
def pingpong(comm):
return b'pong'
@gen.coroutine
def send_recv(comm, reply=True, deserialize=True, **kwargs):
""" Send and recv with a Comm.
Keyword arguments turn into the message
response = yield send_recv(comm, op='ping', reply=True)
"""
msg = kwargs
msg['reply'] = reply
please_close = kwargs.get('close')
force_close = False
try:
yield comm.write(msg)
if reply:
response = yield comm.read()
else:
response = None
except EnvironmentError:
# On communication errors, we should simply close the communication
force_close = True
raise
finally:
if please_close:
yield comm.close()
elif force_close:
comm.abort()
if isinstance(response, dict) and response.get('status') == 'uncaught-error':
six.reraise(*clean_exception(**response))
raise gen.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(object):
""" Conveniently interact with a remote server
>>> remote = rpc(address) # 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 comms as necessary
and so is safe to use in multiple overlapping communications.
When done, close comms explicitly.
>>> remote.close_comms() # doctest: +SKIP
"""
active = weakref.WeakSet()
comms = ()
address = None
def __init__(self, arg=None, comm=None, deserialize=True, timeout=None,
connection_args=None):
self.comms = {}
self.address = coerce_to_address(arg)
self.timeout = timeout
self.status = 'running'
self.deserialize = deserialize
self.connection_args = connection_args
rpc.active.add(self)
@gen.coroutine
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 == '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 = yield connect(self.address, self.timeout,
deserialize=self.deserialize,
connection_args=self.connection_args)
self.comms[comm] = False # mark as taken
raise gen.Return(comm)
def close_comms(self):
@gen.coroutine
def _close_comm(comm):
# Make sure we tell the peer to close
try:
yield comm.write({'op': 'close', 'reply': False})
yield comm.close()
except EnvironmentError:
comm.abort()
for comm in list(self.comms):
if comm and not comm.closed():
_close_comm(comm)
self.comms.clear()
def __getattr__(self, key):
@gen.coroutine
def send_recv_from_rpc(**kwargs):
try:
comm = yield self.live_comm()
result = yield send_recv(comm=comm, op=key, **kwargs)
except (RPCClosed, CommClosedError) as e:
raise e.__class__("%s: while trying to call remote method %r"
% (e, key,))
self.comms[comm] = True # mark as open
raise gen.Return(result)
return send_recv_from_rpc
def close_rpc(self):
if self.status != 'closed':
rpc.active.discard(self)
self.status = 'closed'
self.close_comms()
def __enter__(self):
return self
def __exit__(self, *args):
self.close_rpc()
def __del__(self):
if self.status != 'closed':
rpc.active.discard(self)
self.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(object):
""" The result of ConnectionPool()('host:port')
See Also:
ConnectionPool
"""
def __init__(self, addr, pool):
self.addr = addr
self.pool = pool
def __getattr__(self, key):
@gen.coroutine
def send_recv_from_rpc(**kwargs):
comm = yield self.pool.connect(self.addr)
try:
result = yield send_recv(comm=comm, op=key, **kwargs)
finally:
self.pool.reuse(self.addr, comm)
raise gen.Return(result)
return send_recv_from_rpc
def close_rpc(self):
pass
# For compatibility with rpc()
def __enter__(self):
return self
def __exit__(self, *args):
pass
def __repr__(self):
return "<pooled rpc to %r>" % (self.addr,)
class ConnectionPool(object):
""" 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 ...]
>>> info = yield scheduler.identity()
It creates enough comms to satisfy concurrent connections to any
particular address::
>>> a, b = yield [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
"""
def __init__(self, limit=512, deserialize=True, connection_args=None):
self.open = 0 # Total number of open comms
self.active = 0 # Number of comms currently in use
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.deserialize = deserialize
self.connection_args = connection_args
self.event = Event()
def __repr__(self):
return "<ConnectionPool: open=%d, active=%d>" % (self.open,
self.active)
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)
@gen.coroutine
def connect(self, addr, timeout=None):
"""
Get a Comm to the given address. For internal use.
"""
available = self.available[addr]
occupied = self.occupied[addr]
if available:
comm = available.pop()
if not comm.closed():
self.active += 1
occupied.add(comm)
raise gen.Return(comm)
else:
self.open -= 1
while self.open >= self.limit:
self.event.clear()
self.collect()
yield self.event.wait()
self.open += 1
try:
comm = yield connect(addr, timeout=timeout,
deserialize=self.deserialize,
connection_args=self.connection_args)
except Exception:
self.open -= 1
raise
self.active += 1
occupied.add(comm)
if self.open >= self.limit:
self.event.clear()
raise gen.Return(comm)
def reuse(self, addr, comm):
"""
Reuse an open communication to the given address. For internal use.
"""
self.occupied[addr].remove(comm)
self.active -= 1
if comm.closed():
self.open -= 1
if self.open < self.limit:
self.event.set()
else:
self.available[addr].add(comm)
def collect(self):
"""
Collect open but unused communications, to allow opening other ones.
"""
logger.info("Collecting unused comms. open: %d, active: %d",
self.open, self.active)
for addr, comms in self.available.items():
for comm in comms:
comm.close()
comms.clear()
self.open = self.active
if self.open < self.limit:
self.event.set()
def close(self):
"""
Close all communications abruptly.
"""
for comms in self.available.values():
for comm in comms:
comm.abort()
for comms in self.occupied.values():
for comm in comms:
comm.abort()
def coerce_to_address(o):
if isinstance(o, (list, tuple)):
o = unparse_host_port(*o)
return normalize_address(o)
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)
elif isinstance(traceback, string_types):
traceback = None # happens if the traceback failed serializing
return type(exception), exception, traceback