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/ concurrency / asynpool.py
# -*- coding: utf-8 -*-
"""
celery.concurrency.asynpool
~~~~~~~~~~~~~~~~~~~~~~~~~~~
.. note::
This module will be moved soon, so don't use it directly.
Non-blocking version of :class:`multiprocessing.Pool`.
This code deals with three major challenges:
1) Starting up child processes and keeping them running.
2) Sending jobs to the processes and receiving results back.
3) Safely shutting down this system.
"""
from __future__ import absolute_import
import errno
import gc
import os
import select
import socket
import struct
import sys
import time
from collections import deque, namedtuple
from io import BytesIO
from pickle import HIGHEST_PROTOCOL
from time import sleep
from weakref import WeakValueDictionary, ref
from amqp.utils import promise
from billiard.pool import RUN, TERMINATE, ACK, NACK, WorkersJoined
from billiard import pool as _pool
from billiard.compat import buf_t, setblocking, isblocking
from billiard.einfo import ExceptionInfo
from billiard.queues import _SimpleQueue
from kombu.async import READ, WRITE, ERR
from kombu.serialization import pickle as _pickle
from kombu.utils import fxrange
from kombu.utils.compat import get_errno
from kombu.utils.eventio import SELECT_BAD_FD
from celery.five import Counter, items, string_t, text_t, values
from celery.utils.log import get_logger
from celery.utils.text import truncate
from celery.worker import state as worker_state
try:
from _billiard import read as __read__
from struct import unpack_from as _unpack_from
memoryview = memoryview
readcanbuf = True
if sys.version_info[0] == 2 and sys.version_info < (2, 7, 6):
def unpack_from(fmt, view, _unpack_from=_unpack_from): # noqa
return _unpack_from(fmt, view.tobytes()) # <- memoryview
else:
# unpack_from supports memoryview in 2.7.6 and 3.3+
unpack_from = _unpack_from # noqa
except (ImportError, NameError): # pragma: no cover
def __read__(fd, buf, size, read=os.read): # noqa
chunk = read(fd, size)
n = len(chunk)
if n != 0:
buf.write(chunk)
return n
readcanbuf = False # noqa
def unpack_from(fmt, iobuf, unpack=struct.unpack): # noqa
return unpack(fmt, iobuf.getvalue()) # <-- BytesIO
logger = get_logger(__name__)
error, debug = logger.error, logger.debug
UNAVAIL = frozenset([errno.EAGAIN, errno.EINTR])
#: Constant sent by child process when started (ready to accept work)
WORKER_UP = 15
#: A process must have started before this timeout (in secs.) expires.
PROC_ALIVE_TIMEOUT = 4.0
SCHED_STRATEGY_PREFETCH = 1
SCHED_STRATEGY_FAIR = 4
SCHED_STRATEGIES = {
None: SCHED_STRATEGY_PREFETCH,
'fair': SCHED_STRATEGY_FAIR,
}
RESULT_MAXLEN = 128
Ack = namedtuple('Ack', ('id', 'fd', 'payload'))
def gen_not_started(gen):
# gi_frame is None when generator stopped.
return gen.gi_frame and gen.gi_frame.f_lasti == -1
def _get_job_writer(job):
try:
writer = job._writer
except AttributeError:
pass
else:
return writer() # is a weakref
def _select(readers=None, writers=None, err=None, timeout=0):
"""Simple wrapper to :class:`~select.select`.
:param readers: Set of reader fds to test if readable.
:param writers: Set of writer fds to test if writable.
:param err: Set of fds to test for error condition.
All fd sets passed must be mutable as this function
will remove non-working fds from them, this also means
the caller must make sure there are still fds in the sets
before calling us again.
:returns: tuple of ``(readable, writable, again)``, where
``readable`` is a set of fds that have data available for read,
``writable`` is a set of fds that is ready to be written to
and ``again`` is a flag that if set means the caller must
throw away the result and call us again.
"""
readers = set() if readers is None else readers
writers = set() if writers is None else writers
err = set() if err is None else err
try:
r, w, e = select.select(readers, writers, err, timeout)
if e:
r = list(set(r) | set(e))
return r, w, 0
except (select.error, socket.error) as exc:
if get_errno(exc) == errno.EINTR:
return [], [], 1
elif get_errno(exc) in SELECT_BAD_FD:
for fd in readers | writers | err:
try:
select.select([fd], [], [], 0)
except (select.error, socket.error) as exc:
if get_errno(exc) not in SELECT_BAD_FD:
raise
readers.discard(fd)
writers.discard(fd)
err.discard(fd)
return [], [], 1
else:
raise
def _repr_result(obj):
try:
return repr(obj)
except Exception as orig_exc:
try:
return text_t(obj)
except UnicodeDecodeError:
if isinstance(obj, string_t):
try:
return obj.decode('utf-8', errors='replace')
except Exception:
pass
return '<Unrepresentable: {0!r} (o.__repr__ returns unicode?)>'.format(
orig_exc,
)
class Worker(_pool.Worker):
"""Pool worker process."""
dead = False
def on_loop_start(self, pid):
# our version sends a WORKER_UP message when the process is ready
# to accept work, this will tell the parent that the inqueue fd
# is writable.
self.outq.put((WORKER_UP, (pid, )))
def prepare_result(self, result, maxlen=RESULT_MAXLEN, truncate=truncate):
if not isinstance(result, ExceptionInfo):
return truncate(_repr_result(result), maxlen)
return result
class ResultHandler(_pool.ResultHandler):
"""Handles messages from the pool processes."""
def __init__(self, *args, **kwargs):
self.fileno_to_outq = kwargs.pop('fileno_to_outq')
self.on_process_alive = kwargs.pop('on_process_alive')
super(ResultHandler, self).__init__(*args, **kwargs)
# add our custom message handler
self.state_handlers[WORKER_UP] = self.on_process_alive
def _recv_message(self, add_reader, fd, callback,
__read__=__read__, readcanbuf=readcanbuf,
BytesIO=BytesIO, unpack_from=unpack_from,
load=_pickle.load):
Hr = Br = 0
if readcanbuf:
buf = bytearray(4)
bufv = memoryview(buf)
else:
buf = bufv = BytesIO()
# header
while Hr < 4:
try:
n = __read__(
fd, bufv[Hr:] if readcanbuf else bufv, 4 - Hr,
)
except OSError as exc:
if get_errno(exc) not in UNAVAIL:
raise
yield
else:
if n == 0:
raise (OSError('End of file during message') if Hr
else EOFError())
Hr += n
body_size, = unpack_from('>i', bufv)
if readcanbuf:
buf = bytearray(body_size)
bufv = memoryview(buf)
else:
buf = bufv = BytesIO()
while Br < body_size:
try:
n = __read__(
fd, bufv[Br:] if readcanbuf else bufv, body_size - Br,
)
except OSError as exc:
if get_errno(exc) not in UNAVAIL:
raise
yield
else:
if n == 0:
raise (OSError('End of file during message') if Br
else EOFError())
Br += n
add_reader(fd, self.handle_event, fd)
if readcanbuf:
message = load(BytesIO(bufv))
else:
bufv.seek(0)
message = load(bufv)
if message:
callback(message)
def _make_process_result(self, hub):
"""Coroutine that reads messages from the pool processes
and calls the appropriate handler."""
fileno_to_outq = self.fileno_to_outq
on_state_change = self.on_state_change
add_reader = hub.add_reader
remove_reader = hub.remove_reader
recv_message = self._recv_message
def on_result_readable(fileno):
try:
fileno_to_outq[fileno]
except KeyError: # process gone
return remove_reader(fileno)
it = recv_message(add_reader, fileno, on_state_change)
try:
next(it)
except StopIteration:
pass
except (IOError, OSError, EOFError):
remove_reader(fileno)
else:
add_reader(fileno, it)
return on_result_readable
def register_with_event_loop(self, hub):
self.handle_event = self._make_process_result(hub)
def handle_event(self, fileno):
raise RuntimeError('Not registered with event loop')
def on_stop_not_started(self):
"""This method is always used to stop when the helper thread is not
started."""
cache = self.cache
check_timeouts = self.check_timeouts
fileno_to_outq = self.fileno_to_outq
on_state_change = self.on_state_change
join_exited_workers = self.join_exited_workers
# flush the processes outqueues until they have all terminated.
outqueues = set(fileno_to_outq)
while cache and outqueues and self._state != TERMINATE:
if check_timeouts is not None:
# make sure tasks with a time limit will time out.
check_timeouts()
# cannot iterate and remove at the same time
pending_remove_fd = set()
for fd in outqueues:
self._flush_outqueue(
fd, pending_remove_fd.discard, fileno_to_outq,
on_state_change,
)
try:
join_exited_workers(shutdown=True)
except WorkersJoined:
return debug('result handler: all workers terminated')
outqueues.difference_update(pending_remove_fd)
def _flush_outqueue(self, fd, remove, process_index, on_state_change):
try:
proc = process_index[fd]
except KeyError:
# process already found terminated
# which means its outqueue has already been processed
# by the worker lost handler.
return remove(fd)
reader = proc.outq._reader
try:
setblocking(reader, 1)
except (OSError, IOError):
return remove(fd)
try:
if reader.poll(0):
task = reader.recv()
else:
task = None
sleep(0.5)
except (IOError, EOFError):
return remove(fd)
else:
if task:
on_state_change(task)
finally:
try:
setblocking(reader, 0)
except (OSError, IOError):
return remove(fd)
class AsynPool(_pool.Pool):
"""Pool version that uses AIO instead of helper threads."""
ResultHandler = ResultHandler
Worker = Worker
def __init__(self, processes=None, synack=False,
sched_strategy=None, *args, **kwargs):
self.sched_strategy = SCHED_STRATEGIES.get(sched_strategy,
sched_strategy)
processes = self.cpu_count() if processes is None else processes
self.synack = synack
# create queue-pairs for all our processes in advance.
self._queues = dict((self.create_process_queues(), None)
for _ in range(processes))
# inqueue fileno -> process mapping
self._fileno_to_inq = {}
# outqueue fileno -> process mapping
self._fileno_to_outq = {}
# synqueue fileno -> process mapping
self._fileno_to_synq = {}
# We keep track of processes that have not yet
# sent a WORKER_UP message. If a process fails to send
# this message within proc_up_timeout we terminate it
# and hope the next process will recover.
self._proc_alive_timeout = PROC_ALIVE_TIMEOUT
self._waiting_to_start = set()
# denormalized set of all inqueues.
self._all_inqueues = set()
# Set of fds being written to (busy)
self._active_writes = set()
# Set of active co-routines currently writing jobs.
self._active_writers = set()
# Set of fds that are busy (executing task)
self._busy_workers = set()
self._mark_worker_as_available = self._busy_workers.discard
# Holds jobs waiting to be written to child processes.
self.outbound_buffer = deque()
self.write_stats = Counter()
super(AsynPool, self).__init__(processes, *args, **kwargs)
for proc in self._pool:
# create initial mappings, these will be updated
# as processes are recycled, or found lost elsewhere.
self._fileno_to_outq[proc.outqR_fd] = proc
self._fileno_to_synq[proc.synqW_fd] = proc
self.on_soft_timeout = self.on_hard_timeout = None
if self._timeout_handler:
self.on_soft_timeout = self._timeout_handler.on_soft_timeout
self.on_hard_timeout = self._timeout_handler.on_hard_timeout
def _create_worker_process(self, i):
gc.collect() # Issue #2927
return super(AsynPool, self)._create_worker_process(i)
def _event_process_exit(self, hub, proc):
# This method is called whenever the process sentinel is readable.
self._untrack_child_process(proc, hub)
self.maintain_pool()
def _track_child_process(self, proc, hub):
try:
fd = proc._sentinel_poll
except AttributeError:
# we need to duplicate the fd here to carefully
# control when the fd is removed from the process table,
# as once the original fd is closed we cannot unregister
# the fd from epoll(7) anymore, causing a 100% CPU poll loop.
fd = proc._sentinel_poll = os.dup(proc._popen.sentinel)
hub.add_reader(fd, self._event_process_exit, hub, proc)
def _untrack_child_process(self, proc, hub):
if proc._sentinel_poll is not None:
fd, proc._sentinel_poll = proc._sentinel_poll, None
hub.remove(fd)
os.close(fd)
def register_with_event_loop(self, hub):
"""Registers the async pool with the current event loop."""
self._result_handler.register_with_event_loop(hub)
self.handle_result_event = self._result_handler.handle_event
self._create_timelimit_handlers(hub)
self._create_process_handlers(hub)
self._create_write_handlers(hub)
# Add handler for when a process exits (calls maintain_pool)
[self._track_child_process(w, hub) for w in self._pool]
# Handle_result_event is called whenever one of the
# result queues are readable.
[hub.add_reader(fd, self.handle_result_event, fd)
for fd in self._fileno_to_outq]
# Timers include calling maintain_pool at a regular interval
# to be certain processes are restarted.
for handler, interval in items(self.timers):
hub.call_repeatedly(interval, handler)
hub.on_tick.add(self.on_poll_start)
def _create_timelimit_handlers(self, hub, now=time.time):
"""For async pool this sets up the handlers used
to implement time limits."""
call_later = hub.call_later
trefs = self._tref_for_id = WeakValueDictionary()
def on_timeout_set(R, soft, hard):
if soft:
trefs[R._job] = call_later(
soft, self._on_soft_timeout, R._job, soft, hard, hub,
)
elif hard:
trefs[R._job] = call_later(
hard, self._on_hard_timeout, R._job,
)
self.on_timeout_set = on_timeout_set
def _discard_tref(job):
try:
tref = trefs.pop(job)
tref.cancel()
del(tref)
except (KeyError, AttributeError):
pass # out of scope
self._discard_tref = _discard_tref
def on_timeout_cancel(R):
_discard_tref(R._job)
self.on_timeout_cancel = on_timeout_cancel
def _on_soft_timeout(self, job, soft, hard, hub, now=time.time):
# only used by async pool.
if hard:
self._tref_for_id[job] = hub.call_at(
now() + (hard - soft), self._on_hard_timeout, job,
)
try:
result = self._cache[job]
except KeyError:
pass # job ready
else:
self.on_soft_timeout(result)
finally:
if not hard:
# remove tref
self._discard_tref(job)
def _on_hard_timeout(self, job):
# only used by async pool.
try:
result = self._cache[job]
except KeyError:
pass # job ready
else:
self.on_hard_timeout(result)
finally:
# remove tref
self._discard_tref(job)
def on_job_ready(self, job, i, obj, inqW_fd):
self._mark_worker_as_available(inqW_fd)
def _create_process_handlers(self, hub, READ=READ, ERR=ERR):
"""For async pool this will create the handlers called
when a process is up/down and etc."""
add_reader, remove_reader, remove_writer = (
hub.add_reader, hub.remove_reader, hub.remove_writer,
)
cache = self._cache
all_inqueues = self._all_inqueues
fileno_to_inq = self._fileno_to_inq
fileno_to_outq = self._fileno_to_outq
fileno_to_synq = self._fileno_to_synq
busy_workers = self._busy_workers
handle_result_event = self.handle_result_event
process_flush_queues = self.process_flush_queues
waiting_to_start = self._waiting_to_start
def verify_process_alive(proc):
proc = proc() # is a weakref
if (proc is not None and proc._is_alive() and
proc in waiting_to_start):
assert proc.outqR_fd in fileno_to_outq
assert fileno_to_outq[proc.outqR_fd] is proc
assert proc.outqR_fd in hub.readers
error('Timed out waiting for UP message from %r', proc)
os.kill(proc.pid, 9)
def on_process_up(proc):
"""Called when a process has started."""
# If we got the same fd as a previous process then we will also
# receive jobs in the old buffer, so we need to reset the
# job._write_to and job._scheduled_for attributes used to recover
# message boundaries when processes exit.
infd = proc.inqW_fd
for job in values(cache):
if job._write_to and job._write_to.inqW_fd == infd:
job._write_to = proc
if job._scheduled_for and job._scheduled_for.inqW_fd == infd:
job._scheduled_for = proc
fileno_to_outq[proc.outqR_fd] = proc
# maintain_pool is called whenever a process exits.
self._track_child_process(proc, hub)
assert not isblocking(proc.outq._reader)
# handle_result_event is called when the processes outqueue is
# readable.
add_reader(proc.outqR_fd, handle_result_event, proc.outqR_fd)
waiting_to_start.add(proc)
hub.call_later(
self._proc_alive_timeout, verify_process_alive, ref(proc),
)
self.on_process_up = on_process_up
def _remove_from_index(obj, proc, index, remove_fun, callback=None):
# this remove the file descriptors for a process from
# the indices. we have to make sure we don't overwrite
# another processes fds, as the fds may be reused.
try:
fd = obj.fileno()
except (IOError, OSError):
return
try:
if index[fd] is proc:
# fd has not been reused so we can remove it from index.
index.pop(fd, None)
except KeyError:
pass
else:
remove_fun(fd)
if callback is not None:
callback(fd)
return fd
def on_process_down(proc):
"""Called when a worker process exits."""
if getattr(proc, 'dead', None):
return
process_flush_queues(proc)
_remove_from_index(
proc.outq._reader, proc, fileno_to_outq, remove_reader,
)
if proc.synq:
_remove_from_index(
proc.synq._writer, proc, fileno_to_synq, remove_writer,
)
inq = _remove_from_index(
proc.inq._writer, proc, fileno_to_inq, remove_writer,
callback=all_inqueues.discard,
)
if inq:
busy_workers.discard(inq)
self._untrack_child_process(proc, hub)
waiting_to_start.discard(proc)
self._active_writes.discard(proc.inqW_fd)
remove_writer(proc.inq._writer)
remove_reader(proc.outq._reader)
if proc.synqR_fd:
remove_reader(proc.synq._reader)
if proc.synqW_fd:
self._active_writes.discard(proc.synqW_fd)
remove_reader(proc.synq._writer)
self.on_process_down = on_process_down
def _create_write_handlers(self, hub,
pack=struct.pack, dumps=_pickle.dumps,
protocol=HIGHEST_PROTOCOL):
"""For async pool this creates the handlers used to write data to
child processes."""
fileno_to_inq = self._fileno_to_inq
fileno_to_synq = self._fileno_to_synq
outbound = self.outbound_buffer
pop_message = outbound.popleft
append_message = outbound.append
put_back_message = outbound.appendleft
all_inqueues = self._all_inqueues
active_writes = self._active_writes
active_writers = self._active_writers
busy_workers = self._busy_workers
diff = all_inqueues.difference
add_writer = hub.add_writer
hub_add, hub_remove = hub.add, hub.remove
mark_write_fd_as_active = active_writes.add
mark_write_gen_as_active = active_writers.add
mark_worker_as_busy = busy_workers.add
write_generator_done = active_writers.discard
get_job = self._cache.__getitem__
write_stats = self.write_stats
is_fair_strategy = self.sched_strategy == SCHED_STRATEGY_FAIR
revoked_tasks = worker_state.revoked
getpid = os.getpid
precalc = {ACK: self._create_payload(ACK, (0, )),
NACK: self._create_payload(NACK, (0, ))}
def _put_back(job, _time=time.time):
# puts back at the end of the queue
if job._terminated is not None or \
job.correlation_id in revoked_tasks:
if not job._accepted:
job._ack(None, _time(), getpid(), None)
job._set_terminated(job._terminated)
else:
# XXX linear lookup, should find a better way,
# but this happens rarely and is here to protect against races.
if job not in outbound:
outbound.appendleft(job)
self._put_back = _put_back
# called for every event loop iteration, and if there
# are messages pending this will schedule writing one message
# by registering the 'schedule_writes' function for all currently
# inactive inqueues (not already being written to)
# consolidate means the event loop will merge them
# and call the callback once with the list writable fds as
# argument. Using this means we minimize the risk of having
# the same fd receive every task if the pipe read buffer is not
# full.
if is_fair_strategy:
def on_poll_start():
if outbound and len(busy_workers) < len(all_inqueues):
inactive = diff(active_writes)
[hub_add(fd, None, WRITE | ERR, consolidate=True)
for fd in inactive]
else:
[hub_remove(fd) for fd in diff(active_writes)]
else:
def on_poll_start(): # noqa
if outbound:
[hub_add(fd, None, WRITE | ERR, consolidate=True)
for fd in diff(active_writes)]
else:
[hub_remove(fd) for fd in diff(active_writes)]
self.on_poll_start = on_poll_start
def on_inqueue_close(fd, proc):
# Makes sure the fd is removed from tracking when
# the connection is closed, this is essential as fds may be reused.
busy_workers.discard(fd)
try:
if fileno_to_inq[fd] is proc:
fileno_to_inq.pop(fd, None)
active_writes.discard(fd)
all_inqueues.discard(fd)
hub_remove(fd)
except KeyError:
pass
self.on_inqueue_close = on_inqueue_close
def schedule_writes(ready_fds, curindex=[0]):
# Schedule write operation to ready file descriptor.
# The file descriptor is writeable, but that does not
# mean the process is currently reading from the socket.
# The socket is buffered so writeable simply means that
# the buffer can accept at least 1 byte of data.
# This means we have to cycle between the ready fds.
# the first version used shuffle, but using i % total
# is about 30% faster with many processes. The latter
# also shows more fairness in write stats when used with
# many processes [XXX On OS X, this may vary depending
# on event loop implementation (i.e select vs epoll), so
# have to test further]
total = len(ready_fds)
for i in range(total):
ready_fd = ready_fds[curindex[0] % total]
if ready_fd in active_writes:
# already writing to this fd
curindex[0] += 1
continue
if is_fair_strategy and ready_fd in busy_workers:
# worker is already busy with another task
curindex[0] += 1
continue
if ready_fd not in all_inqueues:
hub_remove(ready_fd)
curindex[0] += 1
continue
try:
job = pop_message()
except IndexError:
# no more messages, remove all inactive fds from the hub.
# this is important since the fds are always writeable
# as long as there's 1 byte left in the buffer, and so
# this may create a spinloop where the event loop
# always wakes up.
for inqfd in diff(active_writes):
hub_remove(inqfd)
break
else:
if not job._accepted: # job not accepted by another worker
try:
# keep track of what process the write operation
# was scheduled for.
proc = job._scheduled_for = fileno_to_inq[ready_fd]
except KeyError:
# write was scheduled for this fd but the process
# has since exited and the message must be sent to
# another process.
put_back_message(job)
curindex[0] += 1
continue
cor = _write_job(proc, ready_fd, job)
job._writer = ref(cor)
mark_write_gen_as_active(cor)
mark_write_fd_as_active(ready_fd)
mark_worker_as_busy(ready_fd)
# Try to write immediately, in case there's an error.
try:
next(cor)
except StopIteration:
pass
except OSError as exc:
if get_errno(exc) != errno.EBADF:
raise
else:
add_writer(ready_fd, cor)
curindex[0] += 1
hub.consolidate_callback = schedule_writes
def send_job(tup):
# Schedule writing job request for when one of the process
# inqueues are writable.
body = dumps(tup, protocol=protocol)
body_size = len(body)
header = pack('>I', body_size)
# index 1,0 is the job ID.
job = get_job(tup[1][0])
job._payload = buf_t(header), buf_t(body), body_size
append_message(job)
self._quick_put = send_job
def on_not_recovering(proc, fd, job, exc):
error('Process inqueue damaged: %r %r: %r',
proc, proc.exitcode, exc, exc_info=1)
if proc._is_alive():
proc.terminate()
hub.remove(fd)
self._put_back(job)
def _write_job(proc, fd, job):
# writes job to the worker process.
# Operation must complete if more than one byte of data
# was written. If the broker connection is lost
# and no data was written the operation shall be canceled.
header, body, body_size = job._payload
errors = 0
try:
# job result keeps track of what process the job is sent to.
job._write_to = proc
send = proc.send_job_offset
Hw = Bw = 0
# write header
while Hw < 4:
try:
Hw += send(header, Hw)
except Exception as exc:
if get_errno(exc) not in UNAVAIL:
raise
# suspend until more data
errors += 1
if errors > 100:
on_not_recovering(proc, fd, job, exc)
raise StopIteration()
yield
else:
errors = 0
# write body
while Bw < body_size:
try:
Bw += send(body, Bw)
except Exception as exc:
if get_errno(exc) not in UNAVAIL:
raise
# suspend until more data
errors += 1
if errors > 100:
on_not_recovering(proc, fd, job, exc)
raise StopIteration()
yield
else:
errors = 0
finally:
hub_remove(fd)
write_stats[proc.index] += 1
# message written, so this fd is now available
active_writes.discard(fd)
write_generator_done(job._writer()) # is a weakref
def send_ack(response, pid, job, fd, WRITE=WRITE, ERR=ERR):
# Only used when synack is enabled.
# Schedule writing ack response for when the fd is writeable.
msg = Ack(job, fd, precalc[response])
callback = promise(write_generator_done)
cor = _write_ack(fd, msg, callback=callback)
mark_write_gen_as_active(cor)
mark_write_fd_as_active(fd)
callback.args = (cor, )
add_writer(fd, cor)
self.send_ack = send_ack
def _write_ack(fd, ack, callback=None):
# writes ack back to the worker if synack enabled.
# this operation *MUST* complete, otherwise
# the worker process will hang waiting for the ack.
header, body, body_size = ack[2]
try:
try:
proc = fileno_to_synq[fd]
except KeyError:
# process died, we can safely discard the ack at this
# point.
raise StopIteration()
send = proc.send_syn_offset
Hw = Bw = 0
# write header
while Hw < 4:
try:
Hw += send(header, Hw)
except Exception as exc:
if get_errno(exc) not in UNAVAIL:
raise
yield
# write body
while Bw < body_size:
try:
Bw += send(body, Bw)
except Exception as exc:
if get_errno(exc) not in UNAVAIL:
raise
# suspend until more data
yield
finally:
if callback:
callback()
# message written, so this fd is now available
active_writes.discard(fd)
def flush(self):
if self._state == TERMINATE:
return
# cancel all tasks that have not been accepted so that NACK is sent.
for job in values(self._cache):
if not job._accepted:
job._cancel()
# clear the outgoing buffer as the tasks will be redelivered by
# the broker anyway.
if self.outbound_buffer:
self.outbound_buffer.clear()
self.maintain_pool()
try:
# ...but we must continue writing the payloads we already started
# to keep message boundaries.
# The messages may be NACK'ed later if synack is enabled.
if self._state == RUN:
# flush outgoing buffers
intervals = fxrange(0.01, 0.1, 0.01, repeatlast=True)
owned_by = {}
for job in values(self._cache):
writer = _get_job_writer(job)
if writer is not None:
owned_by[writer] = job
while self._active_writers:
writers = list(self._active_writers)
for gen in writers:
if (gen.__name__ == '_write_job' and
gen_not_started(gen)):
# has not started writing the job so can
# discard the task, but we must also remove
# it from the Pool._cache.
try:
job = owned_by[gen]
except KeyError:
pass
else:
# removes from Pool._cache
job.discard()
self._active_writers.discard(gen)
else:
try:
job = owned_by[gen]
except KeyError:
pass
else:
job_proc = job._write_to
if job_proc._is_alive():
self._flush_writer(job_proc, gen)
# workers may have exited in the meantime.
self.maintain_pool()
sleep(next(intervals)) # don't busyloop
finally:
self.outbound_buffer.clear()
self._active_writers.clear()
self._active_writes.clear()
self._busy_workers.clear()
def _flush_writer(self, proc, writer):
fds = set([proc.inq._writer])
try:
while fds:
if not proc._is_alive():
break # process exited
readable, writable, again = _select(
writers=fds, err=fds, timeout=0.5,
)
if not again and (writable or readable):
try:
next(writer)
except (StopIteration, OSError, IOError, EOFError):
break
finally:
self._active_writers.discard(writer)
def get_process_queues(self):
"""Get queues for a new process.
Here we will find an unused slot, as there should always
be one available when we start a new process.
"""
return next(q for q, owner in items(self._queues)
if owner is None)
def on_grow(self, n):
"""Grow the pool by ``n`` proceses."""
diff = max(self._processes - len(self._queues), 0)
if diff:
self._queues.update(
dict((self.create_process_queues(), None) for _ in range(diff))
)
def on_shrink(self, n):
"""Shrink the pool by ``n`` processes."""
pass
def create_process_queues(self):
"""Creates new in, out (and optionally syn) queues,
returned as a tuple."""
# NOTE: Pipes must be set O_NONBLOCK at creation time (the original
# fd), otherwise it will not be possible to change the flags until
# there is an actual reader/writer on the other side.
inq = _SimpleQueue(wnonblock=True)
outq = _SimpleQueue(rnonblock=True)
synq = None
assert isblocking(inq._reader)
assert not isblocking(inq._writer)
assert not isblocking(outq._reader)
assert isblocking(outq._writer)
if self.synack:
synq = _SimpleQueue(wnonblock=True)
assert isblocking(synq._reader)
assert not isblocking(synq._writer)
return inq, outq, synq
def on_process_alive(self, pid):
"""Handler called when the :const:`WORKER_UP` message is received
from a child process, which marks the process as ready
to receive work."""
try:
proc = next(w for w in self._pool if w.pid == pid)
except StopIteration:
return logger.warning('process with pid=%s already exited', pid)
assert proc.inqW_fd not in self._fileno_to_inq
assert proc.inqW_fd not in self._all_inqueues
self._waiting_to_start.discard(proc)
self._fileno_to_inq[proc.inqW_fd] = proc
self._fileno_to_synq[proc.synqW_fd] = proc
self._all_inqueues.add(proc.inqW_fd)
def on_job_process_down(self, job, pid_gone):
"""Handler called for each job when the process it was assigned to
exits."""
if job._write_to and not job._write_to._is_alive():
# job was partially written
self.on_partial_read(job, job._write_to)
elif job._scheduled_for and not job._scheduled_for._is_alive():
# job was only scheduled to be written to this process,
# but no data was sent so put it back on the outbound_buffer.
self._put_back(job)
def on_job_process_lost(self, job, pid, exitcode):
"""Handler called for each *started* job when the process it
was assigned to exited by mysterious means (error exitcodes and
signals)"""
self.mark_as_worker_lost(job, exitcode)
def human_write_stats(self):
if self.write_stats is None:
return 'N/A'
vals = list(values(self.write_stats))
total = sum(vals)
def per(v, total):
return '{0:.2f}%'.format((float(v) / total) * 100.0 if v else 0)
return {
'total': total,
'avg': per(total / len(self.write_stats) if total else 0, total),
'all': ', '.join(per(v, total) for v in vals),
'raw': ', '.join(map(str, vals)),
'inqueues': {
'total': len(self._all_inqueues),
'active': len(self._active_writes),
}
}
def _process_cleanup_queues(self, proc):
"""Handler called to clean up a processes queues after process
exit."""
if not proc.dead:
try:
self._queues[self._find_worker_queues(proc)] = None
except (KeyError, ValueError):
pass
@staticmethod
def _stop_task_handler(task_handler):
"""Called at shutdown to tell processes that we are shutting down."""
for proc in task_handler.pool:
try:
setblocking(proc.inq._writer, 1)
except (OSError, IOError):
pass
else:
try:
proc.inq.put(None)
except OSError as exc:
if get_errno(exc) != errno.EBADF:
raise
def create_result_handler(self):
return super(AsynPool, self).create_result_handler(
fileno_to_outq=self._fileno_to_outq,
on_process_alive=self.on_process_alive,
)
def _process_register_queues(self, proc, queues):
"""Marks new ownership for ``queues`` so that the fileno indices are
updated."""
assert queues in self._queues
b = len(self._queues)
self._queues[queues] = proc
assert b == len(self._queues)
def _find_worker_queues(self, proc):
"""Find the queues owned by ``proc``."""
try:
return next(q for q, owner in items(self._queues)
if owner == proc)
except StopIteration:
raise ValueError(proc)
def _setup_queues(self):
# this is only used by the original pool which uses a shared
# queue for all processes.
# these attributes makes no sense for us, but we will still
# have to initialize them.
self._inqueue = self._outqueue = \
self._quick_put = self._quick_get = self._poll_result = None
def process_flush_queues(self, proc):
"""Flushes all queues, including the outbound buffer, so that
all tasks that have not been started will be discarded.
In Celery this is called whenever the transport connection is lost
(consumer restart).
"""
resq = proc.outq._reader
on_state_change = self._result_handler.on_state_change
fds = set([resq])
while fds and not resq.closed and self._state != TERMINATE:
readable, _, again = _select(fds, None, fds, timeout=0.01)
if readable:
try:
task = resq.recv()
except (OSError, IOError, EOFError) as exc:
if get_errno(exc) == errno.EINTR:
continue
elif get_errno(exc) == errno.EAGAIN:
break
else:
debug('got %r while flushing process %r',
exc, proc, exc_info=1)
if get_errno(exc) not in UNAVAIL:
debug('got %r while flushing process %r',
exc, proc, exc_info=1)
break
else:
if task is None:
debug('got sentinel while flushing process %r', proc)
break
else:
on_state_change(task)
else:
break
def on_partial_read(self, job, proc):
"""Called when a job was only partially written to a child process
and it exited."""
# worker terminated by signal:
# we cannot reuse the sockets again, because we don't know if
# the process wrote/read anything frmo them, and if so we cannot
# restore the message boundaries.
if not job._accepted:
# job was not acked, so find another worker to send it to.
self._put_back(job)
writer = _get_job_writer(job)
if writer:
self._active_writers.discard(writer)
del(writer)
if not proc.dead:
proc.dead = True
# Replace queues to avoid reuse
before = len(self._queues)
try:
queues = self._find_worker_queues(proc)
if self.destroy_queues(queues, proc):
self._queues[self.create_process_queues()] = None
except ValueError:
pass
assert len(self._queues) == before
def destroy_queues(self, queues, proc):
"""Destroy queues that can no longer be used, so that they
be replaced by new sockets."""
assert not proc._is_alive()
self._waiting_to_start.discard(proc)
removed = 1
try:
self._queues.pop(queues)
except KeyError:
removed = 0
try:
self.on_inqueue_close(queues[0]._writer.fileno(), proc)
except IOError:
pass
for queue in queues:
if queue:
for sock in (queue._reader, queue._writer):
if not sock.closed:
try:
sock.close()
except (IOError, OSError):
pass
return removed
def _create_payload(self, type_, args,
dumps=_pickle.dumps, pack=struct.pack,
protocol=HIGHEST_PROTOCOL):
body = dumps((type_, args), protocol=protocol)
size = len(body)
header = pack('>I', size)
return header, body, size
@classmethod
def _set_result_sentinel(cls, _outqueue, _pool):
# unused
pass
def _help_stuff_finish_args(self):
# Pool._help_stuff_finished is a classmethod so we have to use this
# trick to modify the arguments passed to it.
return (self._pool, )
@classmethod
def _help_stuff_finish(cls, pool):
debug(
'removing tasks from inqueue until task handler finished',
)
fileno_to_proc = {}
inqR = set()
for w in pool:
try:
fd = w.inq._reader.fileno()
inqR.add(fd)
fileno_to_proc[fd] = w
except IOError:
pass
while inqR:
readable, _, again = _select(inqR, timeout=0.5)
if again:
continue
if not readable:
break
for fd in readable:
fileno_to_proc[fd].inq._reader.recv()
sleep(0)
@property
def timers(self):
return {self.maintain_pool: 5.0}