More pythonw.exe-specific fixes to the kernel launching pipeline.

IPython/zmq/entry_point.py

@@ -1,217 +1,235 b''
 """ Defines helper functions for creating kernel entry points and process
 launchers.
 """
 
 # Standard library imports.
 import os
 import socket
 from subprocess import Popen, PIPE
 import sys
 
 # System library imports.
 import zmq
 
 # Local imports.
 from IPython.core.ultratb import FormattedTB
 from IPython.external.argparse import ArgumentParser
 from IPython.utils import io
 from exitpoller import ExitPollerUnix, ExitPollerWindows
 from displayhook import DisplayHook
 from iostream import OutStream
 from session import Session
 from heartbeat import Heartbeat
 
 def bind_port(socket, ip, port):
     """ Binds the specified ZMQ socket. If the port is zero, a random port is
     chosen. Returns the port that was bound.
     """
     connection = 'tcp://%s' % ip
     if port <= 0:
         port = socket.bind_to_random_port(connection)
     else:
         connection += ':%i' % port
         socket.bind(connection)
     return port
 
 
 def make_argument_parser():
     """ Creates an ArgumentParser for the generic arguments supported by all 
     kernel entry points.
     """
     parser = ArgumentParser()
     parser.add_argument('--ip', type=str, default='127.0.0.1',
                         help='set the kernel\'s IP address [default: local]')
     parser.add_argument('--xrep', type=int, metavar='PORT', default=0,
                         help='set the XREP channel port [default: random]')
     parser.add_argument('--pub', type=int, metavar='PORT', default=0,
                         help='set the PUB channel port [default: random]')
     parser.add_argument('--req', type=int, metavar='PORT', default=0,
                         help='set the REQ channel port [default: random]')
     parser.add_argument('--hb', type=int, metavar='PORT', default=0,
                         help='set the heartbeat port [default: random]')
 
     if sys.platform == 'win32':
         parser.add_argument('--parent', type=int, metavar='HANDLE', 
                             default=0, help='kill this process if the process '
                             'with HANDLE dies')
     else:
         parser.add_argument('--parent', action='store_true', 
                             help='kill this process if its parent dies')
 
     return parser
 
 
 def make_kernel(namespace, kernel_factory, 
                 out_stream_factory=None, display_hook_factory=None):
-    """ Creates a kernel.
+    """ Creates a kernel, redirects stdout/stderr, and installs a display hook
+    and exception handler.
     """
+    # If running under pythonw.exe, the interpreter will crash if more than 4KB
+    # of data is written to stdout or stderr. This is a bug that has been with
+    # Python for a very long time; see http://bugs.python.org/issue706263.
+    if sys.executable.endswith('pythonw.exe'):
+        blackhole = file(os.devnull, 'w')
+        sys.stdout = sys.stderr = blackhole
+        sys.__stdout__ = sys.__stderr__ = blackhole 
+
     # Install minimal exception handling
     sys.excepthook = FormattedTB(mode='Verbose', color_scheme='NoColor', 
                                  ostream=sys.__stdout__)
 
     # Create a context, a session, and the kernel sockets.
     io.raw_print("Starting the kernel at pid:", os.getpid())
     context = zmq.Context()
     session = Session(username=u'kernel')
 
     reply_socket = context.socket(zmq.XREP)
     xrep_port = bind_port(reply_socket, namespace.ip, namespace.xrep)
     io.raw_print("XREP Channel on port", xrep_port)
 
     pub_socket = context.socket(zmq.PUB)
     pub_port = bind_port(pub_socket, namespace.ip, namespace.pub)
     io.raw_print("PUB Channel on port", pub_port)
 
     req_socket = context.socket(zmq.XREQ)
     req_port = bind_port(req_socket, namespace.ip, namespace.req)
     io.raw_print("REQ Channel on port", req_port)
 
     hb = Heartbeat(context, (namespace.ip, namespace.hb))
     hb.start()
     io.raw_print("Heartbeat REP Channel on port", hb.port)
 
     # Redirect input streams and set a display hook.
     if out_stream_factory:
         sys.stdout = out_stream_factory(session, pub_socket, u'stdout')
         sys.stderr = out_stream_factory(session, pub_socket, u'stderr')
     if display_hook_factory:
         sys.displayhook = display_hook_factory(session, pub_socket)
 
     # Create the kernel.
     return kernel_factory(session=session, reply_socket=reply_socket, 
                           pub_socket=pub_socket, req_socket=req_socket)
 
 
 def start_kernel(namespace, kernel):
     """ Starts a kernel.
     """
     # Configure this kernel/process to die on parent termination, if necessary.
     if namespace.parent:
         if sys.platform == 'win32':
             poller = ExitPollerWindows(namespace.parent)
         else:
             poller = ExitPollerUnix()
         poller.start()
 
     # Start the kernel mainloop.
     kernel.start()
 
 
 def make_default_main(kernel_factory):
     """ Creates the simplest possible kernel entry point.
     """
     def main():
         namespace = make_argument_parser().parse_args()
         kernel = make_kernel(namespace, kernel_factory, OutStream, DisplayHook)
         start_kernel(namespace, kernel)
     return main
 
 
 def base_launch_kernel(code, xrep_port=0, pub_port=0, req_port=0, hb_port=0,
                        independent=False, extra_arguments=[]):
     """ Launches a localhost kernel, binding to the specified ports.
 
     Parameters
     ----------
     code : str,
         A string of Python code that imports and executes a kernel entry point.
 
     xrep_port : int, optional
         The port to use for XREP channel.
 
     pub_port : int, optional
         The port to use for the SUB channel.
 
     req_port : int, optional
         The port to use for the REQ (raw input) channel.
 
     hb_port : int, optional
         The port to use for the hearbeat REP channel.
 
     independent : bool, optional (default False) 
         If set, the kernel process is guaranteed to survive if this process
         dies. If not set, an effort is made to ensure that the kernel is killed
         when this process dies. Note that in this case it is still good practice
         to kill kernels manually before exiting.
 
     extra_arguments = list, optional
         A list of extra arguments to pass when executing the launch code.
 
     Returns
     -------
     A tuple of form:
         (kernel_process, xrep_port, pub_port, req_port)
     where kernel_process is a Popen object and the ports are integers.
     """
     # Find open ports as necessary.
     ports = []
     ports_needed = int(xrep_port <= 0) + int(pub_port <= 0) + \
                    int(req_port <= 0) + int(hb_port <= 0)
     for i in xrange(ports_needed):
         sock = socket.socket()
         sock.bind(('', 0))
         ports.append(sock)
     for i, sock in enumerate(ports):
         port = sock.getsockname()[1]
         sock.close()
         ports[i] = port
     if xrep_port <= 0:
         xrep_port = ports.pop(0)
     if pub_port <= 0:
         pub_port = ports.pop(0)
     if req_port <= 0:
         req_port = ports.pop(0)
     if hb_port <= 0:
         hb_port = ports.pop(0)
 
     # Build the kernel launch command.
     arguments = [ sys.executable, '-c', code, '--xrep', str(xrep_port), 
                   '--pub', str(pub_port), '--req', str(req_port),
                   '--hb', str(hb_port) ]
     arguments.extend(extra_arguments)
 
     # Spawn a kernel.
     if sys.platform == 'win32':
+
         # If using pythonw, stdin, stdout, and stderr are invalid. Popen will
         # fail unless they are suitably redirected. We don't read from the
         # pipes, but they must exist.
         redirect = PIPE if sys.executable.endswith('pythonw.exe') else None
+
         if independent:
             proc = Popen(['start', '/b'] + arguments, shell=True,
                          stdout=redirect, stderr=redirect, stdin=redirect)
         else:
             from _subprocess import DuplicateHandle, GetCurrentProcess, \
                 DUPLICATE_SAME_ACCESS
             pid = GetCurrentProcess()
             handle = DuplicateHandle(pid, pid, pid, 0, 
                                      True, # Inheritable by new processes.
                                      DUPLICATE_SAME_ACCESS)
             proc = Popen(arguments + ['--parent', str(int(handle))],
                          stdout=redirect, stderr=redirect, stdin=redirect)
+
+        # Clean up pipes created to work around Popen bug.
+        if redirect is not None:
+            proc.stdout.close()
+            proc.stderr.close()
+            proc.stdin.close()
+
     else:
         if independent:
             proc = Popen(arguments, preexec_fn=lambda: os.setsid())
         else:
             proc = Popen(arguments + ['--parent'])
 
     return proc, xrep_port, pub_port, req_port, hb_port