from __future__ import annotations
import asyncio
import errno
import logging
import os
import shutil
import threading
import uuid
import warnings
import weakref
from contextlib import suppress
from inspect import isawaitable
from queue import Empty
from time import sleep as sync_sleep
from typing import ClassVar
import psutil
from tornado import gen
from tornado.ioloop import IOLoop, PeriodicCallback
import dask
from dask.system import CPU_COUNT
from dask.utils import parse_timedelta
from . import preloading
from .comm import get_address_host, unparse_host_port
from .comm.addressing import address_from_user_args
from .core import CommClosedError, RPCClosed, Status, coerce_to_address, error_message
from .diagnostics.plugin import _get_plugin_name
from .node import ServerNode
from .process import AsyncProcess
from .proctitle import enable_proctitle_on_children
from .protocol import pickle
from .security import Security
from .utils import (
TimeoutError,
get_ip,
json_load_robust,
log_errors,
mp_context,
parse_ports,
silence_logging,
)
from .worker import Worker, parse_memory_limit, run
logger = logging.getLogger(__name__)
[docs]class Nanny(ServerNode):
"""A process to manage worker processes
The nanny spins up Worker processes, watches then, and kills or restarts
them as necessary. It is necessary if you want to use the
``Client.restart`` method, or to restart the worker automatically if
it gets to the terminate fraction of its memory limit.
The parameters for the Nanny are mostly the same as those for the Worker
with exceptions listed below.
Parameters
----------
env: dict, optional
Environment variables set at time of Nanny initialization will be
ensured to be set in the Worker process as well. This argument allows to
overwrite or otherwise set environment variables for the Worker. It is
also possible to set environment variables using the option
`distributed.nanny.environ`. Precedence as follows
1. Nanny arguments
2. Existing environment variables
3. Dask configuration
See Also
--------
Worker
"""
_instances: ClassVar[weakref.WeakSet[Nanny]] = weakref.WeakSet()
process = None
status = Status.undefined
def __init__(
self,
scheduler_ip=None,
scheduler_port=None,
scheduler_file=None,
worker_port=0,
nthreads=None,
ncores=None,
loop=None,
local_dir=None,
local_directory=None,
services=None,
name=None,
memory_limit="auto",
reconnect=True,
validate=False,
quiet=False,
resources=None,
silence_logs=None,
death_timeout=None,
preload=None,
preload_argv=None,
preload_nanny=None,
preload_nanny_argv=None,
security=None,
contact_address=None,
listen_address=None,
worker_class=None,
env=None,
interface=None,
host=None,
port=None,
protocol=None,
config=None,
**worker_kwargs,
):
self._setup_logging(logger)
self.loop = loop or IOLoop.current()
if isinstance(security, dict):
security = Security(**security)
self.security = security or Security()
assert isinstance(self.security, Security)
self.connection_args = self.security.get_connection_args("worker")
if local_dir is not None:
warnings.warn("The local_dir keyword has moved to local_directory")
local_directory = local_dir
if local_directory is None:
local_directory = dask.config.get("temporary-directory") or os.getcwd()
self._original_local_dir = local_directory
local_directory = os.path.join(local_directory, "dask-worker-space")
else:
self._original_local_dir = local_directory
self.local_directory = local_directory
if not os.path.exists(self.local_directory):
os.makedirs(self.local_directory, exist_ok=True)
self.preload = preload
if self.preload is None:
self.preload = dask.config.get("distributed.worker.preload")
self.preload_argv = preload_argv
if self.preload_argv is None:
self.preload_argv = dask.config.get("distributed.worker.preload-argv")
if preload_nanny is None:
preload_nanny = dask.config.get("distributed.nanny.preload")
if preload_nanny_argv is None:
preload_nanny_argv = dask.config.get("distributed.nanny.preload-argv")
self.preloads = preloading.process_preloads(
self, preload_nanny, preload_nanny_argv, file_dir=self.local_directory
)
if scheduler_file:
cfg = json_load_robust(scheduler_file)
self.scheduler_addr = cfg["address"]
elif scheduler_ip is None and dask.config.get("scheduler-address"):
self.scheduler_addr = dask.config.get("scheduler-address")
elif scheduler_port is None:
self.scheduler_addr = coerce_to_address(scheduler_ip)
else:
self.scheduler_addr = coerce_to_address((scheduler_ip, scheduler_port))
if protocol is None:
protocol_address = self.scheduler_addr.split("://")
if len(protocol_address) == 2:
protocol = protocol_address[0]
if ncores is not None:
warnings.warn("the ncores= parameter has moved to nthreads=")
nthreads = ncores
self._given_worker_port = worker_port
self.nthreads = nthreads or CPU_COUNT
self.reconnect = reconnect
self.validate = validate
self.resources = resources
self.death_timeout = parse_timedelta(death_timeout)
self.Worker = Worker if worker_class is None else worker_class
config_environ = dask.config.get("distributed.nanny.environ", {})
if not isinstance(config_environ, dict):
raise TypeError(
f"distributed.nanny.environ configuration must be of type dict. Instead got {type(config_environ)}"
)
self.env = config_environ.copy()
for k in self.env:
if k in os.environ:
self.env[k] = os.environ[k]
if env:
self.env.update(env)
self.env = {k: str(v) for k, v in self.env.items()}
self.config = config or dask.config.config
worker_kwargs.update(
{
"port": worker_port,
"interface": interface,
"protocol": protocol,
"host": host,
}
)
self.worker_kwargs = worker_kwargs
self.contact_address = contact_address
self.memory_terminate_fraction = dask.config.get(
"distributed.worker.memory.terminate"
)
self.services = services
self.name = name
self.quiet = quiet
self.auto_restart = True
self.memory_limit = parse_memory_limit(memory_limit, self.nthreads)
if silence_logs:
silence_logging(level=silence_logs)
self.silence_logs = silence_logs
handlers = {
"instantiate": self.instantiate,
"kill": self.kill,
"restart": self.restart,
# cannot call it 'close' on the rpc side for naming conflict
"get_logs": self.get_logs,
"terminate": self.close,
"close_gracefully": self.close_gracefully,
"run": self.run,
"plugin_add": self.plugin_add,
"plugin_remove": self.plugin_remove,
}
self.plugins = {}
super().__init__(
handlers=handlers, io_loop=self.loop, connection_args=self.connection_args
)
self.scheduler = self.rpc(self.scheduler_addr)
if self.memory_limit:
pc = PeriodicCallback(self.memory_monitor, 100)
self.periodic_callbacks["memory"] = pc
if (
not host
and not interface
and not self.scheduler_addr.startswith("inproc://")
):
host = get_ip(get_address_host(self.scheduler.address))
self._start_port = port
self._start_host = host
self._interface = interface
self._protocol = protocol
self._listen_address = listen_address
Nanny._instances.add(self)
self.status = Status.init
def __repr__(self):
return "<Nanny: %s, threads: %d>" % (self.worker_address, self.nthreads)
async def _unregister(self, timeout=10):
if self.process is None:
return
worker_address = self.process.worker_address
if worker_address is None:
return
allowed_errors = (TimeoutError, CommClosedError, EnvironmentError, RPCClosed)
with suppress(allowed_errors):
await asyncio.wait_for(
self.scheduler.unregister(address=self.worker_address), timeout
)
@property
def worker_address(self):
return None if self.process is None else self.process.worker_address
@property
def worker_dir(self):
return None if self.process is None else self.process.worker_dir
@property
def local_dir(self):
"""For API compatibility with Nanny"""
warnings.warn("The local_dir attribute has moved to local_directory")
return self.local_directory
[docs] async def start(self):
"""Start nanny, start local process, start watching"""
await super().start()
ports = parse_ports(self._start_port)
for port in ports:
start_address = address_from_user_args(
host=self._start_host,
port=port,
interface=self._interface,
protocol=self._protocol,
security=self.security,
)
try:
await self.listen(
start_address, **self.security.get_listen_args("worker")
)
except OSError as e:
if len(ports) > 1 and e.errno == errno.EADDRINUSE:
continue
else:
raise
else:
self._start_address = start_address
break
else:
raise ValueError(
f"Could not start Nanny on host {self._start_host}"
f"with port {self._start_port}"
)
self.ip = get_address_host(self.address)
for preload in self.preloads:
await preload.start()
msg = await self.scheduler.register_nanny()
for name, plugin in msg["nanny-plugins"].items():
await self.plugin_add(plugin=plugin, name=name)
logger.info(" Start Nanny at: %r", self.address)
response = await self.instantiate()
if response == Status.running:
assert self.worker_address
self.status = Status.running
else:
await self.close()
self.start_periodic_callbacks()
return self
[docs] async def kill(self, comm=None, timeout=2):
"""Kill the local worker process
Blocks until both the process is down and the scheduler is properly
informed
"""
self.auto_restart = False
if self.process is None:
return "OK"
deadline = self.loop.time() + timeout
await self.process.kill(timeout=0.8 * (deadline - self.loop.time()))
[docs] async def instantiate(self, comm=None) -> Status:
"""Start a local worker process
Blocks until the process is up and the scheduler is properly informed
"""
if self._listen_address:
start_arg = self._listen_address
else:
host = self.listener.bound_address[0]
start_arg = self.listener.prefix + unparse_host_port(
host, self._given_worker_port
)
if self.process is None:
worker_kwargs = dict(
scheduler_ip=self.scheduler_addr,
nthreads=self.nthreads,
local_directory=self._original_local_dir,
services=self.services,
nanny=self.address,
name=self.name,
memory_limit=self.memory_limit,
reconnect=self.reconnect,
resources=self.resources,
validate=self.validate,
silence_logs=self.silence_logs,
death_timeout=self.death_timeout,
preload=self.preload,
preload_argv=self.preload_argv,
security=self.security,
contact_address=self.contact_address,
)
worker_kwargs.update(self.worker_kwargs)
self.process = WorkerProcess(
worker_kwargs=worker_kwargs,
worker_start_args=(start_arg,),
silence_logs=self.silence_logs,
on_exit=self._on_exit_sync,
worker=self.Worker,
env=self.env,
config=self.config,
)
if self.death_timeout:
try:
result = await asyncio.wait_for(
self.process.start(), self.death_timeout
)
except TimeoutError:
await self.close(timeout=self.death_timeout)
logger.error(
"Timed out connecting Nanny '%s' to scheduler '%s'",
self,
self.scheduler_addr,
)
raise
else:
try:
result = await self.process.start()
except Exception:
await self.close()
raise
return result
async def plugin_add(self, comm=None, plugin=None, name=None):
with log_errors(pdb=False):
if isinstance(plugin, bytes):
plugin = pickle.loads(plugin)
if name is None:
name = _get_plugin_name(plugin)
assert name
self.plugins[name] = plugin
logger.info("Starting Nanny plugin %s" % name)
if hasattr(plugin, "setup"):
try:
result = plugin.setup(nanny=self)
if isawaitable(result):
result = await result
except Exception as e:
msg = error_message(e)
return msg
if getattr(plugin, "restart", False):
await self.restart()
return {"status": "OK"}
async def plugin_remove(self, comm=None, name=None):
with log_errors(pdb=False):
logger.info(f"Removing Nanny plugin {name}")
try:
plugin = self.plugins.pop(name)
if hasattr(plugin, "teardown"):
result = plugin.teardown(nanny=self)
if isawaitable(result):
result = await result
except Exception as e:
msg = error_message(e)
return msg
return {"status": "OK"}
async def restart(self, comm=None, timeout=30, executor_wait=True):
async def _():
if self.process is not None:
await self.kill()
await self.instantiate()
try:
await asyncio.wait_for(_(), timeout)
except TimeoutError:
logger.error(
f"Restart timed out after {timeout}s; returning before finished"
)
return "timed out"
else:
return "OK"
@property
def _psutil_process(self):
pid = self.process.process.pid
try:
self._psutil_process_obj
except AttributeError:
self._psutil_process_obj = psutil.Process(pid)
if self._psutil_process_obj.pid != pid:
self._psutil_process_obj = psutil.Process(pid)
return self._psutil_process_obj
[docs] def memory_monitor(self):
"""Track worker's memory. Restart if it goes above terminate fraction"""
if self.status != Status.running:
return
if self.process is None or self.process.process is None:
return None
process = self.process.process
try:
proc = self._psutil_process
memory = proc.memory_info().rss
except (ProcessLookupError, psutil.NoSuchProcess, psutil.AccessDenied):
return
frac = memory / self.memory_limit
if self.memory_terminate_fraction and frac > self.memory_terminate_fraction:
logger.warning(
"Worker exceeded %d%% memory budget. Restarting",
100 * self.memory_terminate_fraction,
)
process.terminate()
def is_alive(self):
return self.process is not None and self.process.is_alive()
def run(self, *args, **kwargs):
return run(self, *args, **kwargs)
def _on_exit_sync(self, exitcode):
self.loop.add_callback(self._on_exit, exitcode)
async def _on_exit(self, exitcode):
if self.status not in (
Status.init,
Status.closing,
Status.closed,
Status.closing_gracefully,
):
try:
await self._unregister()
except OSError:
if not self.reconnect:
await self.close()
return
try:
if self.status not in (
Status.closing,
Status.closed,
Status.closing_gracefully,
):
if self.auto_restart:
logger.warning("Restarting worker")
await self.instantiate()
elif self.status == Status.closing_gracefully:
await self.close()
except Exception:
logger.error(
"Failed to restart worker after its process exited", exc_info=True
)
@property
def pid(self):
return self.process and self.process.pid
def _close(self, *args, **kwargs):
warnings.warn("Worker._close has moved to Worker.close", stacklevel=2)
return self.close(*args, **kwargs)
[docs] def close_gracefully(self, comm=None):
"""
A signal that we shouldn't try to restart workers if they go away
This is used as part of the cluster shutdown process.
"""
self.status = Status.closing_gracefully
[docs] async def close(self, comm=None, timeout=5, report=None):
"""
Close the worker process, stop all comms.
"""
if self.status == Status.closing:
await self.finished()
assert self.status == Status.closed
if self.status == Status.closed:
return "OK"
self.status = Status.closing
logger.info("Closing Nanny at %r", self.address)
for preload in self.preloads:
await preload.teardown()
teardowns = [
plugin.teardown(self)
for plugin in self.plugins.values()
if hasattr(plugin, "teardown")
]
await asyncio.gather(*(td for td in teardowns if isawaitable(td)))
self.stop()
try:
if self.process is not None:
await self.kill(timeout=timeout)
except Exception:
pass
self.process = None
await self.rpc.close()
self.status = Status.closed
if comm:
await comm.write("OK")
await super().close()
async def _log_event(self, topic, msg):
await self.scheduler.log_event(
topic=topic,
msg=msg,
)
def log_event(self, topic, msg):
self.loop.add_callback(self._log_event, topic, msg)
class WorkerProcess:
running: asyncio.Event
stopped: asyncio.Event
# The interval how often to check the msg queue for init
_init_msg_interval = 0.05
def __init__(
self,
worker_kwargs,
worker_start_args,
silence_logs,
on_exit,
worker,
env,
config,
):
self.status = Status.init
self.silence_logs = silence_logs
self.worker_kwargs = worker_kwargs
self.worker_start_args = worker_start_args
self.on_exit = on_exit
self.process = None
self.Worker = worker
self.env = env
self.config = config
# Initialized when worker is ready
self.worker_dir = None
self.worker_address = None
async def start(self) -> Status:
"""
Ensure the worker process is started.
"""
enable_proctitle_on_children()
if self.status == Status.running:
return self.status
if self.status == Status.starting:
await self.running.wait()
return self.status
self.init_result_q = init_q = mp_context.Queue()
self.child_stop_q = mp_context.Queue()
uid = uuid.uuid4().hex
self.process = AsyncProcess(
target=self._run,
name="Dask Worker process (from Nanny)",
kwargs=dict(
worker_kwargs=self.worker_kwargs,
worker_start_args=self.worker_start_args,
silence_logs=self.silence_logs,
init_result_q=self.init_result_q,
child_stop_q=self.child_stop_q,
uid=uid,
Worker=self.Worker,
env=self.env,
config=self.config,
),
)
self.process.daemon = dask.config.get("distributed.worker.daemon", default=True)
self.process.set_exit_callback(self._on_exit)
self.running = asyncio.Event()
self.stopped = asyncio.Event()
self.status = Status.starting
try:
await self.process.start()
except OSError:
logger.exception("Nanny failed to start process", exc_info=True)
self.process.terminate()
self.status = Status.failed
return self.status
try:
msg = await self._wait_until_connected(uid)
except Exception:
self.status = Status.failed
self.process.terminate()
raise
if not msg:
return self.status
self.worker_address = msg["address"]
self.worker_dir = msg["dir"]
assert self.worker_address
self.status = Status.running
self.running.set()
init_q.close()
return self.status
def _on_exit(self, proc):
if proc is not self.process:
# Ignore exit of old process instance
return
self.mark_stopped()
def _death_message(self, pid, exitcode):
assert exitcode is not None
if exitcode == 255:
return "Worker process %d was killed by unknown signal" % (pid,)
elif exitcode >= 0:
return "Worker process %d exited with status %d" % (pid, exitcode)
else:
return "Worker process %d was killed by signal %d" % (pid, -exitcode)
def is_alive(self):
return self.process is not None and self.process.is_alive()
@property
def pid(self):
return self.process.pid if self.process and self.process.is_alive() else None
def mark_stopped(self):
if self.status != Status.stopped:
r = self.process.exitcode
assert r is not None
if r != 0:
msg = self._death_message(self.process.pid, r)
logger.info(msg)
self.status = Status.stopped
self.stopped.set()
# Release resources
self.process.close()
self.init_result_q = None
self.child_stop_q = None
self.process = None
# Best effort to clean up worker directory
if self.worker_dir and os.path.exists(self.worker_dir):
shutil.rmtree(self.worker_dir, ignore_errors=True)
self.worker_dir = None
# User hook
if self.on_exit is not None:
self.on_exit(r)
async def kill(self, timeout=2, executor_wait=True):
"""
Ensure the worker process is stopped, waiting at most
*timeout* seconds before terminating it abruptly.
"""
loop = IOLoop.current()
deadline = loop.time() + timeout
if self.status == Status.stopped:
return
if self.status == Status.stopping:
await self.stopped.wait()
return
assert self.status in (Status.starting, Status.running)
self.status = Status.stopping
process = self.process
self.child_stop_q.put(
{
"op": "stop",
"timeout": max(0, deadline - loop.time()) * 0.8,
"executor_wait": executor_wait,
}
)
await asyncio.sleep(0) # otherwise we get broken pipe errors
self.child_stop_q.close()
while process.is_alive() and loop.time() < deadline:
await asyncio.sleep(0.05)
if process.is_alive():
logger.warning(
"Worker process still alive after %d seconds, killing", timeout
)
try:
await process.terminate()
except Exception as e:
logger.error("Failed to kill worker process: %s", e)
async def _wait_until_connected(self, uid):
while True:
if self.status != Status.starting:
return
# This is a multiprocessing queue and we'd block the event loop if
# we simply called get
try:
msg = self.init_result_q.get_nowait()
except Empty:
await asyncio.sleep(self._init_msg_interval)
continue
if msg["uid"] != uid: # ensure that we didn't cross queues
continue
if "exception" in msg:
logger.error(
"Failed while trying to start worker process: %s", msg["exception"]
)
raise msg["exception"]
else:
return msg
@classmethod
def _run(
cls,
worker_kwargs,
worker_start_args,
silence_logs,
init_result_q,
child_stop_q,
uid,
env,
config,
Worker,
): # pragma: no cover
try:
os.environ.update(env)
dask.config.set(config)
try:
from dask.multiprocessing import initialize_worker_process
except ImportError: # old Dask version
pass
else:
initialize_worker_process()
if silence_logs:
logger.setLevel(silence_logs)
IOLoop.clear_instance()
loop = IOLoop()
loop.make_current()
worker = Worker(**worker_kwargs)
async def do_stop(timeout=5, executor_wait=True):
try:
await worker.close(
report=True,
nanny=False,
safe=True, # TODO: Graceful or not?
executor_wait=executor_wait,
timeout=timeout,
)
finally:
loop.stop()
def watch_stop_q():
"""
Wait for an incoming stop message and then stop the
worker cleanly.
"""
while True:
try:
msg = child_stop_q.get(timeout=1000)
except Empty:
pass
else:
child_stop_q.close()
assert msg.pop("op") == "stop"
loop.add_callback(do_stop, **msg)
break
t = threading.Thread(target=watch_stop_q, name="Nanny stop queue watch")
t.daemon = True
t.start()
async def run():
"""
Try to start worker and inform parent of outcome.
"""
try:
await worker
except Exception as e:
logger.exception("Failed to start worker")
init_result_q.put({"uid": uid, "exception": e})
init_result_q.close()
# If we hit an exception here we need to wait for a least
# one interval for the outside to pick up this message.
# Otherwise we arrive in a race condition where the process
# cleanup wipes the queue before the exception can be
# properly handled. See also
# WorkerProcess._wait_until_connected (the 2 is for good
# measure)
sync_sleep(cls._init_msg_interval * 2)
else:
try:
assert worker.address
except ValueError:
pass
else:
init_result_q.put(
{
"address": worker.address,
"dir": worker.local_directory,
"uid": uid,
}
)
init_result_q.close()
await worker.finished()
logger.info("Worker closed")
except Exception as e:
logger.exception("Failed to initialize Worker")
init_result_q.put({"uid": uid, "exception": e})
init_result_q.close()
# If we hit an exception here we need to wait for a least one
# interval for the outside to pick up this message. Otherwise we
# arrive in a race condition where the process cleanup wipes the
# queue before the exception can be properly handled. See also
# WorkerProcess._wait_until_connected (the 2 is for good measure)
sync_sleep(cls._init_msg_interval * 2)
else:
try:
loop.run_sync(run)
except (TimeoutError, gen.TimeoutError):
# Loop was stopped before wait_until_closed() returned, ignore
pass
except KeyboardInterrupt:
# At this point the loop is not running thus we have to run
# do_stop() explicitly.
loop.run_sync(do_stop)