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make InteractiveShell.banner a property
make InteractiveShell.banner a property

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ipkernel.py
853 lines | 32.0 KiB | text/x-python | PythonLexer
"""An interactive kernel that talks to frontends over 0MQ."""
# Copyright (c) IPython Development Team.
# Distributed under the terms of the Modified BSD License.
from __future__ import print_function
import getpass
import sys
import time
import traceback
import logging
import uuid
from datetime import datetime
from signal import (
signal, default_int_handler, SIGINT
)
import zmq
from zmq.eventloop import ioloop
from zmq.eventloop.zmqstream import ZMQStream
from IPython.config.configurable import Configurable
from IPython.core.error import StdinNotImplementedError
from IPython.core import release
from IPython.utils import py3compat
from IPython.utils.py3compat import builtin_mod, unicode_type, string_types
from IPython.utils.jsonutil import json_clean
from IPython.utils.tokenutil import token_at_cursor
from IPython.utils.traitlets import (
Any, Instance, Float, Dict, List, Set, Integer, Unicode,
Type, Bool,
)
from .serialize import serialize_object, unpack_apply_message
from .session import Session
from .zmqshell import ZMQInteractiveShell
#-----------------------------------------------------------------------------
# Main kernel class
#-----------------------------------------------------------------------------
protocol_version = release.kernel_protocol_version
ipython_version = release.version
language_version = sys.version.split()[0]
class Kernel(Configurable):
#---------------------------------------------------------------------------
# Kernel interface
#---------------------------------------------------------------------------
# attribute to override with a GUI
eventloop = Any(None)
def _eventloop_changed(self, name, old, new):
"""schedule call to eventloop from IOLoop"""
loop = ioloop.IOLoop.instance()
loop.add_callback(self.enter_eventloop)
shell = Instance('IPython.core.interactiveshell.InteractiveShellABC')
shell_class = Type(ZMQInteractiveShell)
session = Instance(Session)
profile_dir = Instance('IPython.core.profiledir.ProfileDir')
shell_streams = List()
control_stream = Instance(ZMQStream)
iopub_socket = Instance(zmq.Socket)
stdin_socket = Instance(zmq.Socket)
log = Instance(logging.Logger)
user_module = Any()
def _user_module_changed(self, name, old, new):
if self.shell is not None:
self.shell.user_module = new
user_ns = Instance(dict, args=None, allow_none=True)
def _user_ns_changed(self, name, old, new):
if self.shell is not None:
self.shell.user_ns = new
self.shell.init_user_ns()
# identities:
int_id = Integer(-1)
ident = Unicode()
def _ident_default(self):
return unicode_type(uuid.uuid4())
# Private interface
_darwin_app_nap = Bool(True, config=True,
help="""Whether to use appnope for compatiblity with OS X App Nap.
Only affects OS X >= 10.9.
"""
)
# track associations with current request
_allow_stdin = Bool(False)
_parent_header = Dict()
_parent_ident = Any(b'')
# Time to sleep after flushing the stdout/err buffers in each execute
# cycle. While this introduces a hard limit on the minimal latency of the
# execute cycle, it helps prevent output synchronization problems for
# clients.
# Units are in seconds. The minimum zmq latency on local host is probably
# ~150 microseconds, set this to 500us for now. We may need to increase it
# a little if it's not enough after more interactive testing.
_execute_sleep = Float(0.0005, config=True)
# Frequency of the kernel's event loop.
# Units are in seconds, kernel subclasses for GUI toolkits may need to
# adapt to milliseconds.
_poll_interval = Float(0.05, config=True)
# If the shutdown was requested over the network, we leave here the
# necessary reply message so it can be sent by our registered atexit
# handler. This ensures that the reply is only sent to clients truly at
# the end of our shutdown process (which happens after the underlying
# IPython shell's own shutdown).
_shutdown_message = None
# This is a dict of port number that the kernel is listening on. It is set
# by record_ports and used by connect_request.
_recorded_ports = Dict()
# A reference to the Python builtin 'raw_input' function.
# (i.e., __builtin__.raw_input for Python 2.7, builtins.input for Python 3)
_sys_raw_input = Any()
_sys_eval_input = Any()
# set of aborted msg_ids
aborted = Set()
def __init__(self, **kwargs):
super(Kernel, self).__init__(**kwargs)
# Initialize the InteractiveShell subclass
self.shell = self.shell_class.instance(parent=self,
profile_dir = self.profile_dir,
user_module = self.user_module,
user_ns = self.user_ns,
kernel = self,
)
self.shell.displayhook.session = self.session
self.shell.displayhook.pub_socket = self.iopub_socket
self.shell.displayhook.topic = self._topic('execute_result')
self.shell.display_pub.session = self.session
self.shell.display_pub.pub_socket = self.iopub_socket
self.shell.data_pub.session = self.session
self.shell.data_pub.pub_socket = self.iopub_socket
# TMP - hack while developing
self.shell._reply_content = None
# Build dict of handlers for message types
msg_types = [ 'execute_request', 'complete_request',
'inspect_request', 'history_request',
'kernel_info_request',
'connect_request', 'shutdown_request',
'apply_request',
]
self.shell_handlers = {}
for msg_type in msg_types:
self.shell_handlers[msg_type] = getattr(self, msg_type)
comm_msg_types = [ 'comm_open', 'comm_msg', 'comm_close' ]
comm_manager = self.shell.comm_manager
for msg_type in comm_msg_types:
self.shell_handlers[msg_type] = getattr(comm_manager, msg_type)
control_msg_types = msg_types + [ 'clear_request', 'abort_request' ]
self.control_handlers = {}
for msg_type in control_msg_types:
self.control_handlers[msg_type] = getattr(self, msg_type)
def dispatch_control(self, msg):
"""dispatch control requests"""
idents,msg = self.session.feed_identities(msg, copy=False)
try:
msg = self.session.unserialize(msg, content=True, copy=False)
except:
self.log.error("Invalid Control Message", exc_info=True)
return
self.log.debug("Control received: %s", msg)
header = msg['header']
msg_id = header['msg_id']
msg_type = header['msg_type']
handler = self.control_handlers.get(msg_type, None)
if handler is None:
self.log.error("UNKNOWN CONTROL MESSAGE TYPE: %r", msg_type)
else:
try:
handler(self.control_stream, idents, msg)
except Exception:
self.log.error("Exception in control handler:", exc_info=True)
def dispatch_shell(self, stream, msg):
"""dispatch shell requests"""
# flush control requests first
if self.control_stream:
self.control_stream.flush()
idents,msg = self.session.feed_identities(msg, copy=False)
try:
msg = self.session.unserialize(msg, content=True, copy=False)
except:
self.log.error("Invalid Message", exc_info=True)
return
header = msg['header']
msg_id = header['msg_id']
msg_type = msg['header']['msg_type']
# Print some info about this message and leave a '--->' marker, so it's
# easier to trace visually the message chain when debugging. Each
# handler prints its message at the end.
self.log.debug('\n*** MESSAGE TYPE:%s***', msg_type)
self.log.debug(' Content: %s\n --->\n ', msg['content'])
if msg_id in self.aborted:
self.aborted.remove(msg_id)
# is it safe to assume a msg_id will not be resubmitted?
reply_type = msg_type.split('_')[0] + '_reply'
status = {'status' : 'aborted'}
md = {'engine' : self.ident}
md.update(status)
reply_msg = self.session.send(stream, reply_type, metadata=md,
content=status, parent=msg, ident=idents)
return
handler = self.shell_handlers.get(msg_type, None)
if handler is None:
self.log.error("UNKNOWN MESSAGE TYPE: %r", msg_type)
else:
# ensure default_int_handler during handler call
sig = signal(SIGINT, default_int_handler)
self.log.debug("%s: %s", msg_type, msg)
try:
handler(stream, idents, msg)
except Exception:
self.log.error("Exception in message handler:", exc_info=True)
finally:
signal(SIGINT, sig)
def enter_eventloop(self):
"""enter eventloop"""
self.log.info("entering eventloop %s", self.eventloop)
for stream in self.shell_streams:
# flush any pending replies,
# which may be skipped by entering the eventloop
stream.flush(zmq.POLLOUT)
# restore default_int_handler
signal(SIGINT, default_int_handler)
while self.eventloop is not None:
try:
self.eventloop(self)
except KeyboardInterrupt:
# Ctrl-C shouldn't crash the kernel
self.log.error("KeyboardInterrupt caught in kernel")
continue
else:
# eventloop exited cleanly, this means we should stop (right?)
self.eventloop = None
break
self.log.info("exiting eventloop")
def start(self):
"""register dispatchers for streams"""
self.shell.exit_now = False
if self.control_stream:
self.control_stream.on_recv(self.dispatch_control, copy=False)
def make_dispatcher(stream):
def dispatcher(msg):
return self.dispatch_shell(stream, msg)
return dispatcher
for s in self.shell_streams:
s.on_recv(make_dispatcher(s), copy=False)
# publish idle status
self._publish_status('starting')
def do_one_iteration(self):
"""step eventloop just once"""
if self.control_stream:
self.control_stream.flush()
for stream in self.shell_streams:
# handle at most one request per iteration
stream.flush(zmq.POLLIN, 1)
stream.flush(zmq.POLLOUT)
def record_ports(self, ports):
"""Record the ports that this kernel is using.
The creator of the Kernel instance must call this methods if they
want the :meth:`connect_request` method to return the port numbers.
"""
self._recorded_ports = ports
#---------------------------------------------------------------------------
# Kernel request handlers
#---------------------------------------------------------------------------
def _make_metadata(self, other=None):
"""init metadata dict, for execute/apply_reply"""
new_md = {
'dependencies_met' : True,
'engine' : self.ident,
'started': datetime.now(),
}
if other:
new_md.update(other)
return new_md
def _publish_execute_input(self, code, parent, execution_count):
"""Publish the code request on the iopub stream."""
self.session.send(self.iopub_socket, u'execute_input',
{u'code':code, u'execution_count': execution_count},
parent=parent, ident=self._topic('execute_input')
)
def _publish_status(self, status, parent=None):
"""send status (busy/idle) on IOPub"""
self.session.send(self.iopub_socket,
u'status',
{u'execution_state': status},
parent=parent,
ident=self._topic('status'),
)
def _forward_input(self, allow_stdin=False):
"""Forward raw_input and getpass to the current frontend.
via input_request
"""
self._allow_stdin = allow_stdin
if py3compat.PY3:
self._sys_raw_input = builtin_mod.input
builtin_mod.input = self.raw_input
else:
self._sys_raw_input = builtin_mod.raw_input
self._sys_eval_input = builtin_mod.input
builtin_mod.raw_input = self.raw_input
builtin_mod.input = lambda prompt='': eval(self.raw_input(prompt))
self._save_getpass = getpass.getpass
getpass.getpass = self.getpass
def _restore_input(self):
"""Restore raw_input, getpass"""
if py3compat.PY3:
builtin_mod.input = self._sys_raw_input
else:
builtin_mod.raw_input = self._sys_raw_input
builtin_mod.input = self._sys_eval_input
getpass.getpass = self._save_getpass
def set_parent(self, ident, parent):
"""Record the parent state
For associating side effects with their requests.
"""
self._parent_ident = ident
self._parent_header = parent
self.shell.set_parent(parent)
def execute_request(self, stream, ident, parent):
"""handle an execute_request"""
self._publish_status(u'busy', parent)
try:
content = parent[u'content']
code = py3compat.cast_unicode_py2(content[u'code'])
silent = content[u'silent']
store_history = content.get(u'store_history', not silent)
except:
self.log.error("Got bad msg: ")
self.log.error("%s", parent)
return
md = self._make_metadata(parent['metadata'])
shell = self.shell # we'll need this a lot here
self._forward_input(content.get('allow_stdin', False))
# Set the parent message of the display hook and out streams.
self.set_parent(ident, parent)
# Re-broadcast our input for the benefit of listening clients, and
# start computing output
if not silent:
self._publish_execute_input(code, parent, shell.execution_count)
reply_content = {}
# FIXME: the shell calls the exception handler itself.
shell._reply_content = None
try:
shell.run_cell(code, store_history=store_history, silent=silent)
except:
status = u'error'
# FIXME: this code right now isn't being used yet by default,
# because the run_cell() call above directly fires off exception
# reporting. This code, therefore, is only active in the scenario
# where runlines itself has an unhandled exception. We need to
# uniformize this, for all exception construction to come from a
# single location in the codbase.
etype, evalue, tb = sys.exc_info()
tb_list = traceback.format_exception(etype, evalue, tb)
reply_content.update(shell._showtraceback(etype, evalue, tb_list))
else:
status = u'ok'
finally:
self._restore_input()
reply_content[u'status'] = status
# Return the execution counter so clients can display prompts
reply_content['execution_count'] = shell.execution_count - 1
# FIXME - fish exception info out of shell, possibly left there by
# runlines. We'll need to clean up this logic later.
if shell._reply_content is not None:
reply_content.update(shell._reply_content)
e_info = dict(engine_uuid=self.ident, engine_id=self.int_id, method='execute')
reply_content['engine_info'] = e_info
# reset after use
shell._reply_content = None
if 'traceback' in reply_content:
self.log.info("Exception in execute request:\n%s", '\n'.join(reply_content['traceback']))
# At this point, we can tell whether the main code execution succeeded
# or not. If it did, we proceed to evaluate user_expressions
if reply_content['status'] == 'ok':
reply_content[u'user_expressions'] = \
shell.user_expressions(content.get(u'user_expressions', {}))
else:
# If there was an error, don't even try to compute expressions
reply_content[u'user_expressions'] = {}
# Payloads should be retrieved regardless of outcome, so we can both
# recover partial output (that could have been generated early in a
# block, before an error) and clear the payload system always.
reply_content[u'payload'] = shell.payload_manager.read_payload()
# Be agressive about clearing the payload because we don't want
# it to sit in memory until the next execute_request comes in.
shell.payload_manager.clear_payload()
# Flush output before sending the reply.
sys.stdout.flush()
sys.stderr.flush()
# FIXME: on rare occasions, the flush doesn't seem to make it to the
# clients... This seems to mitigate the problem, but we definitely need
# to better understand what's going on.
if self._execute_sleep:
time.sleep(self._execute_sleep)
# Send the reply.
reply_content = json_clean(reply_content)
md['status'] = reply_content['status']
if reply_content['status'] == 'error' and \
reply_content['ename'] == 'UnmetDependency':
md['dependencies_met'] = False
reply_msg = self.session.send(stream, u'execute_reply',
reply_content, parent, metadata=md,
ident=ident)
self.log.debug("%s", reply_msg)
if not silent and reply_msg['content']['status'] == u'error':
self._abort_queues()
self._publish_status(u'idle', parent)
def complete_request(self, stream, ident, parent):
content = parent['content']
code = content['code']
cursor_pos = content['cursor_pos']
txt, matches = self.shell.complete('', code, cursor_pos)
matches = {'matches' : matches,
'cursor_end' : cursor_pos,
'cursor_start' : cursor_pos - len(txt),
'metadata' : {},
'status' : 'ok'}
matches = json_clean(matches)
completion_msg = self.session.send(stream, 'complete_reply',
matches, parent, ident)
self.log.debug("%s", completion_msg)
def inspect_request(self, stream, ident, parent):
content = parent['content']
name = token_at_cursor(content['code'], content['cursor_pos'])
info = self.shell.object_inspect(name)
reply_content = {'status' : 'ok'}
reply_content['data'] = data = {}
reply_content['metadata'] = {}
reply_content['found'] = info['found']
if info['found']:
info_text = self.shell.object_inspect_text(
name,
detail_level=content.get('detail_level', 0),
)
reply_content['data']['text/plain'] = info_text
# Before we send this object over, we scrub it for JSON usage
reply_content = json_clean(reply_content)
msg = self.session.send(stream, 'inspect_reply',
reply_content, parent, ident)
self.log.debug("%s", msg)
def history_request(self, stream, ident, parent):
# We need to pull these out, as passing **kwargs doesn't work with
# unicode keys before Python 2.6.5.
hist_access_type = parent['content']['hist_access_type']
raw = parent['content']['raw']
output = parent['content']['output']
if hist_access_type == 'tail':
n = parent['content']['n']
hist = self.shell.history_manager.get_tail(n, raw=raw, output=output,
include_latest=True)
elif hist_access_type == 'range':
session = parent['content']['session']
start = parent['content']['start']
stop = parent['content']['stop']
hist = self.shell.history_manager.get_range(session, start, stop,
raw=raw, output=output)
elif hist_access_type == 'search':
n = parent['content'].get('n')
unique = parent['content'].get('unique', False)
pattern = parent['content']['pattern']
hist = self.shell.history_manager.search(
pattern, raw=raw, output=output, n=n, unique=unique)
else:
hist = []
hist = list(hist)
content = {'history' : hist}
content = json_clean(content)
msg = self.session.send(stream, 'history_reply',
content, parent, ident)
self.log.debug("Sending history reply with %i entries", len(hist))
def connect_request(self, stream, ident, parent):
if self._recorded_ports is not None:
content = self._recorded_ports.copy()
else:
content = {}
msg = self.session.send(stream, 'connect_reply',
content, parent, ident)
self.log.debug("%s", msg)
def kernel_info_request(self, stream, ident, parent):
vinfo = {
'protocol_version': protocol_version,
'implementation': 'ipython',
'implementation_version': ipython_version,
'language_version': language_version,
'language': 'python',
'banner': self.shell.banner,
}
msg = self.session.send(stream, 'kernel_info_reply',
vinfo, parent, ident)
self.log.debug("%s", msg)
def shutdown_request(self, stream, ident, parent):
self.shell.exit_now = True
content = dict(status='ok')
content.update(parent['content'])
self.session.send(stream, u'shutdown_reply', content, parent, ident=ident)
# same content, but different msg_id for broadcasting on IOPub
self._shutdown_message = self.session.msg(u'shutdown_reply',
content, parent
)
self._at_shutdown()
# call sys.exit after a short delay
loop = ioloop.IOLoop.instance()
loop.add_timeout(time.time()+0.1, loop.stop)
#---------------------------------------------------------------------------
# Engine methods
#---------------------------------------------------------------------------
def apply_request(self, stream, ident, parent):
try:
content = parent[u'content']
bufs = parent[u'buffers']
msg_id = parent['header']['msg_id']
except:
self.log.error("Got bad msg: %s", parent, exc_info=True)
return
self._publish_status(u'busy', parent)
# Set the parent message of the display hook and out streams.
shell = self.shell
shell.set_parent(parent)
# execute_input_msg = self.session.msg(u'execute_input',{u'code':code}, parent=parent)
# self.iopub_socket.send(execute_input_msg)
# self.session.send(self.iopub_socket, u'execute_input', {u'code':code},parent=parent)
md = self._make_metadata(parent['metadata'])
try:
working = shell.user_ns
prefix = "_"+str(msg_id).replace("-","")+"_"
f,args,kwargs = unpack_apply_message(bufs, working, copy=False)
fname = getattr(f, '__name__', 'f')
fname = prefix+"f"
argname = prefix+"args"
kwargname = prefix+"kwargs"
resultname = prefix+"result"
ns = { fname : f, argname : args, kwargname : kwargs , resultname : None }
# print ns
working.update(ns)
code = "%s = %s(*%s,**%s)" % (resultname, fname, argname, kwargname)
try:
exec(code, shell.user_global_ns, shell.user_ns)
result = working.get(resultname)
finally:
for key in ns:
working.pop(key)
result_buf = serialize_object(result,
buffer_threshold=self.session.buffer_threshold,
item_threshold=self.session.item_threshold,
)
except:
# invoke IPython traceback formatting
shell.showtraceback()
# FIXME - fish exception info out of shell, possibly left there by
# run_code. We'll need to clean up this logic later.
reply_content = {}
if shell._reply_content is not None:
reply_content.update(shell._reply_content)
e_info = dict(engine_uuid=self.ident, engine_id=self.int_id, method='apply')
reply_content['engine_info'] = e_info
# reset after use
shell._reply_content = None
self.session.send(self.iopub_socket, u'error', reply_content, parent=parent,
ident=self._topic('error'))
self.log.info("Exception in apply request:\n%s", '\n'.join(reply_content['traceback']))
result_buf = []
if reply_content['ename'] == 'UnmetDependency':
md['dependencies_met'] = False
else:
reply_content = {'status' : 'ok'}
# put 'ok'/'error' status in header, for scheduler introspection:
md['status'] = reply_content['status']
# flush i/o
sys.stdout.flush()
sys.stderr.flush()
reply_msg = self.session.send(stream, u'apply_reply', reply_content,
parent=parent, ident=ident,buffers=result_buf, metadata=md)
self._publish_status(u'idle', parent)
#---------------------------------------------------------------------------
# Control messages
#---------------------------------------------------------------------------
def abort_request(self, stream, ident, parent):
"""abort a specifig msg by id"""
msg_ids = parent['content'].get('msg_ids', None)
if isinstance(msg_ids, string_types):
msg_ids = [msg_ids]
if not msg_ids:
self.abort_queues()
for mid in msg_ids:
self.aborted.add(str(mid))
content = dict(status='ok')
reply_msg = self.session.send(stream, 'abort_reply', content=content,
parent=parent, ident=ident)
self.log.debug("%s", reply_msg)
def clear_request(self, stream, idents, parent):
"""Clear our namespace."""
self.shell.reset(False)
msg = self.session.send(stream, 'clear_reply', ident=idents, parent=parent,
content = dict(status='ok'))
#---------------------------------------------------------------------------
# Protected interface
#---------------------------------------------------------------------------
def _wrap_exception(self, method=None):
# import here, because _wrap_exception is only used in parallel,
# and parallel has higher min pyzmq version
from IPython.parallel.error import wrap_exception
e_info = dict(engine_uuid=self.ident, engine_id=self.int_id, method=method)
content = wrap_exception(e_info)
return content
def _topic(self, topic):
"""prefixed topic for IOPub messages"""
if self.int_id >= 0:
base = "engine.%i" % self.int_id
else:
base = "kernel.%s" % self.ident
return py3compat.cast_bytes("%s.%s" % (base, topic))
def _abort_queues(self):
for stream in self.shell_streams:
if stream:
self._abort_queue(stream)
def _abort_queue(self, stream):
poller = zmq.Poller()
poller.register(stream.socket, zmq.POLLIN)
while True:
idents,msg = self.session.recv(stream, zmq.NOBLOCK, content=True)
if msg is None:
return
self.log.info("Aborting:")
self.log.info("%s", msg)
msg_type = msg['header']['msg_type']
reply_type = msg_type.split('_')[0] + '_reply'
status = {'status' : 'aborted'}
md = {'engine' : self.ident}
md.update(status)
reply_msg = self.session.send(stream, reply_type, metadata=md,
content=status, parent=msg, ident=idents)
self.log.debug("%s", reply_msg)
# We need to wait a bit for requests to come in. This can probably
# be set shorter for true asynchronous clients.
poller.poll(50)
def _no_raw_input(self):
"""Raise StdinNotImplentedError if active frontend doesn't support
stdin."""
raise StdinNotImplementedError("raw_input was called, but this "
"frontend does not support stdin.")
def getpass(self, prompt=''):
"""Forward getpass to frontends
Raises
------
StdinNotImplentedError if active frontend doesn't support stdin.
"""
if not self._allow_stdin:
raise StdinNotImplementedError(
"getpass was called, but this frontend does not support input requests."
)
return self._input_request(prompt,
self._parent_ident,
self._parent_header,
password=True,
)
def raw_input(self, prompt=''):
"""Forward raw_input to frontends
Raises
------
StdinNotImplentedError if active frontend doesn't support stdin.
"""
if not self._allow_stdin:
raise StdinNotImplementedError(
"raw_input was called, but this frontend does not support input requests."
)
return self._input_request(prompt,
self._parent_ident,
self._parent_header,
password=False,
)
def _input_request(self, prompt, ident, parent, password=False):
# Flush output before making the request.
sys.stderr.flush()
sys.stdout.flush()
# flush the stdin socket, to purge stale replies
while True:
try:
self.stdin_socket.recv_multipart(zmq.NOBLOCK)
except zmq.ZMQError as e:
if e.errno == zmq.EAGAIN:
break
else:
raise
# Send the input request.
content = json_clean(dict(prompt=prompt, password=password))
self.session.send(self.stdin_socket, u'input_request', content, parent,
ident=ident)
# Await a response.
while True:
try:
ident, reply = self.session.recv(self.stdin_socket, 0)
except Exception:
self.log.warn("Invalid Message:", exc_info=True)
except KeyboardInterrupt:
# re-raise KeyboardInterrupt, to truncate traceback
raise KeyboardInterrupt
else:
break
try:
value = py3compat.unicode_to_str(reply['content']['value'])
except:
self.log.error("Bad input_reply: %s", parent)
value = ''
if value == '\x04':
# EOF
raise EOFError
return value
def _at_shutdown(self):
"""Actions taken at shutdown by the kernel, called by python's atexit.
"""
# io.rprint("Kernel at_shutdown") # dbg
if self._shutdown_message is not None:
self.session.send(self.iopub_socket, self._shutdown_message, ident=self._topic('shutdown'))
self.log.debug("%s", self._shutdown_message)
[ s.flush(zmq.POLLOUT) for s in self.shell_streams ]