示例#1
0
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':
        # Create a Win32 event for interrupting the kernel.
        interrupt_event = ParentPollerWindows.create_interrupt_event()
        arguments += [ '--interrupt', str(int(interrupt_event)) ]

        # 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(arguments, 
                         creationflags=512, # CREATE_NEW_PROCESS_GROUP
                         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)

        # Attach the interrupt event to the Popen objet so it can be used later.
        proc.win32_interrupt_event = interrupt_event

        # 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
示例#2
0
def launch_kernel(cmd,
                  stdin=None,
                  stdout=None,
                  stderr=None,
                  env=None,
                  independent=False,
                  cwd=None,
                  **kw):
    """ Launches a localhost kernel, binding to the specified ports.

    Parameters
    ----------
    cmd : Popen list,
        A string of Python code that imports and executes a kernel entry point.

    stdin, stdout, stderr : optional (default None)
        Standards streams, as defined in subprocess.Popen.

    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.

    cwd : path, optional
        The working dir of the kernel process (default: cwd of this process).

    Returns
    -------

    Popen instance for the kernel subprocess
    """

    # Popen will fail (sometimes with a deadlock) if stdin, stdout, and stderr
    # are invalid. Unfortunately, there is in general no way to detect whether
    # they are valid.  The following two blocks redirect them to (temporary)
    # pipes in certain important cases.

    # If this process has been backgrounded, our stdin is invalid. Since there
    # is no compelling reason for the kernel to inherit our stdin anyway, we'll
    # place this one safe and always redirect.
    redirect_in = True
    _stdin = PIPE if stdin is None else stdin

    # If this process in running on pythonw, we know that stdin, stdout, and
    # stderr are all invalid.
    redirect_out = sys.executable.endswith('pythonw.exe')
    if redirect_out:
        blackhole = open(os.devnull, 'w')
        _stdout = blackhole if stdout is None else stdout
        _stderr = blackhole if stderr is None else stderr
    else:
        _stdout, _stderr = stdout, stderr

    env = env if (env is not None) else os.environ.copy()

    encoding = getdefaultencoding(prefer_stream=False)
    kwargs = dict(
        stdin=_stdin,
        stdout=_stdout,
        stderr=_stderr,
        cwd=cwd,
        env=env,
    )

    # Spawn a kernel.
    if sys.platform == 'win32':
        # Popen on Python 2 on Windows cannot handle unicode args or cwd
        cmd = [cast_bytes_py2(c, encoding) for c in cmd]
        if cwd:
            cwd = cast_bytes_py2(cwd, sys.getfilesystemencoding() or 'ascii')
            kwargs['cwd'] = cwd

        from .win_interrupt import create_interrupt_event
        # Create a Win32 event for interrupting the kernel
        # and store it in an environment variable.
        interrupt_event = create_interrupt_event()
        env["JPY_INTERRUPT_EVENT"] = str(interrupt_event)
        # deprecated old env name:
        env["IPY_INTERRUPT_EVENT"] = env["JPY_INTERRUPT_EVENT"]

        try:
            from _winapi import DuplicateHandle, GetCurrentProcess, \
                DUPLICATE_SAME_ACCESS, CREATE_NEW_PROCESS_GROUP
        except:
            from _subprocess import DuplicateHandle, GetCurrentProcess, \
                DUPLICATE_SAME_ACCESS, CREATE_NEW_PROCESS_GROUP
        # Launch the kernel process
        if independent:
            kwargs['creationflags'] = CREATE_NEW_PROCESS_GROUP
        else:
            pid = GetCurrentProcess()
            handle = DuplicateHandle(
                pid,
                pid,
                pid,
                0,
                True,  # Inheritable by new processes.
                DUPLICATE_SAME_ACCESS)
            env['JPY_PARENT_PID'] = str(int(handle))

    else:
        if independent:
            kwargs['preexec_fn'] = lambda: os.setsid()
        else:
            # Create a new process group. This makes it easier to
            # interrupt the kernel, because we want to interrupt the
            # children of the kernel process also.
            kwargs['preexec_fn'] = lambda: os.setpgrp()
            env['JPY_PARENT_PID'] = str(os.getpid())

    try:
        proc = Popen(cmd, **kwargs)
    except Exception as exc:
        msg = ("Failed to run command:\n{}\n" "with kwargs:\n{!r}\n")
        msg = msg.format(cmd, kwargs)
        get_logger().error(msg)
        raise

    if sys.platform == 'win32':
        # Attach the interrupt event to the Popen objet so it can be used later.
        proc.win32_interrupt_event = interrupt_event

    # Clean up pipes created to work around Popen bug.
    if redirect_in:
        if stdin is None:
            proc.stdin.close()

    return proc
示例#3
0
def bin_launch_kernel(executable,
                      fname,
                      stdin=None,
                      stdout=None,
                      stderr=None,
                      independent=False,
                      extra_arguments=[],
                      cwd=None):
    """ 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.

    stdin, stdout, stderr : optional (default None)
        Standards streams, as defined in subprocess.Popen.

    fname : unicode, optional
        The JSON connector file, containing ip/port/hmac key information.

    key : str, optional
        The Session key used for HMAC authentication.

    executable : str, optional (default sys.executable)
        The Python executable to use for the kernel process.

    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.

    cwd : path, optional
        The working dir of the kernel process (default: cwd of this process).

    Returns
    -------
    A tuple of form:
        (kernel_process, shell_port, iopub_port, stdin_port, hb_port)
    where kernel_process is a Popen object and the ports are integers.
    """

    # Build the kernel launch command.
    arguments = [executable, '-f', fname]
    arguments.extend(extra_arguments)
    print("entry_point - launching kernel %s" % arguments)
    # Popen will fail (sometimes with a deadlock) if stdin, stdout, and stderr
    # are invalid. Unfortunately, there is in general no way to detect whether
    # they are valid.  The following two blocks redirect them to (temporary)
    # pipes in certain important cases.

    # If this process has been backgrounded, our stdin is invalid. Since there
    # is no compelling reason for the kernel to inherit our stdin anyway, we'll
    # place this one safe and always redirect.
    redirect_in = True
    redirect_out = False
    _stdin = PIPE if stdin is None else stdin
    _stdout, _stderr = stdout, stderr
    # If this process in running on pythonw, we know that stdin, stdout, and
    # stderr are all invalid.

    # Spawn a kernel.
    if sys.platform == 'win32':
        # Create a Win32 event for interrupting the kernel.
        interrupt_event = ParentPollerWindows.create_interrupt_event()
        arguments += ['--interrupt=%i' % interrupt_event]

        # If the kernel is running on pythonw and stdout/stderr are not been
        # re-directed, it will crash when 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.
        # A cleaner solution to this problem would be to pass os.devnull to
        # Popen directly. Unfortunately, that does not work.
        if executable.endswith('pythonw.exe'):
            if stdout is None:
                arguments.append('--no-stdout')
            if stderr is None:
                arguments.append('--no-stderr')

        # Launch the kernel process.
        if independent:
            proc = Popen(
                arguments,
                creationflags=512,  # CREATE_NEW_PROCESS_GROUP
                stdin=_stdin,
                stdout=_stdout,
                stderr=_stderr)
        else:
            try:
                from _winapi import DuplicateHandle, GetCurrentProcess, \
                    DUPLICATE_SAME_ACCESS
            except:
                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=%i' % int(handle)],
                         stdin=_stdin,
                         stdout=_stdout,
                         stderr=_stderr)

        # Attach the interrupt event to the Popen objet so it can be used later.
        proc.win32_interrupt_event = interrupt_event

    else:
        if independent:
            proc = Popen(arguments,
                         preexec_fn=lambda: os.setsid(),
                         stdin=_stdin,
                         stdout=_stdout,
                         stderr=_stderr,
                         cwd=cwd)
        else:
            proc = Popen(arguments + ['--parent=1'],
                         stdin=_stdin,
                         stdout=_stdout,
                         stderr=_stderr,
                         cwd=cwd)

    # Clean up pipes created to work around Popen bug.
    if redirect_in:
        if stdin is None:
            proc.stdin.close()
    if redirect_out:
        if stdout is None:
            proc.stdout.close()
        if stderr is None:
            proc.stderr.close()

    return proc
示例#4
0
def launch_kernel(cmd,
                  stdin=None,
                  stdout=None,
                  stderr=None,
                  env=None,
                  independent=False,
                  cwd=None,
                  **kw):
    """ Launches a localhost kernel, binding to the specified ports.

    Parameters
    ----------
    cmd : Popen list,
        A string of Python code that imports and executes a kernel entry point.

    stdin, stdout, stderr : optional (default None)
        Standards streams, as defined in subprocess.Popen.

    env: dict, optional
        Environment variables passed to the kernel

    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.

    cwd : path, optional
        The working dir of the kernel process (default: cwd of this process).

    **kw: optional
        Additional arguments for Popen

    Returns
    -------

    Popen instance for the kernel subprocess
    """

    # Popen will fail (sometimes with a deadlock) if stdin, stdout, and stderr
    # are invalid. Unfortunately, there is in general no way to detect whether
    # they are valid.  The following two blocks redirect them to (temporary)
    # pipes in certain important cases.

    # If this process has been backgrounded, our stdin is invalid. Since there
    # is no compelling reason for the kernel to inherit our stdin anyway, we'll
    # place this one safe and always redirect.
    redirect_in = True
    _stdin = PIPE if stdin is None else stdin

    # If this process in running on pythonw, we know that stdin, stdout, and
    # stderr are all invalid.
    redirect_out = sys.executable.endswith("pythonw.exe")
    if redirect_out:
        blackhole = open(os.devnull, "w")
        _stdout = blackhole if stdout is None else stdout
        _stderr = blackhole if stderr is None else stderr
    else:
        _stdout, _stderr = stdout, stderr

    env = env if (env is not None) else os.environ.copy()

    encoding = getdefaultencoding(prefer_stream=False)
    kwargs = kw.copy()
    main_args = dict(
        stdin=_stdin,
        stdout=_stdout,
        stderr=_stderr,
        cwd=cwd,
        env=env,
    )
    kwargs.update(main_args)

    # Spawn a kernel.
    if sys.platform == "win32":
        # Popen on Python 2 on Windows cannot handle unicode args or cwd
        cmd = [cast_bytes_py2(c, encoding) for c in cmd]
        if cwd:
            cwd = cast_bytes_py2(cwd, sys.getfilesystemencoding() or "ascii")
            kwargs["cwd"] = cwd

        from .win_interrupt import create_interrupt_event

        # Create a Win32 event for interrupting the kernel
        # and store it in an environment variable.
        interrupt_event = create_interrupt_event()
        env["JPY_INTERRUPT_EVENT"] = str(interrupt_event)
        # deprecated old env name:
        env["IPY_INTERRUPT_EVENT"] = env["JPY_INTERRUPT_EVENT"]

        try:
            from _winapi import (
                DuplicateHandle,
                GetCurrentProcess,
                DUPLICATE_SAME_ACCESS,
                CREATE_NEW_PROCESS_GROUP,
            )
        except:
            from _subprocess import (
                DuplicateHandle,
                GetCurrentProcess,
                DUPLICATE_SAME_ACCESS,
                CREATE_NEW_PROCESS_GROUP,
            )

        # create a handle on the parent to be inherited
        if independent:
            kwargs["creationflags"] = CREATE_NEW_PROCESS_GROUP
        else:
            pid = GetCurrentProcess()
            handle = DuplicateHandle(
                pid,
                pid,
                pid,
                0,
                True,  # Inheritable by new processes.
                DUPLICATE_SAME_ACCESS,
            )
            env["JPY_PARENT_PID"] = str(int(handle))

        # Prevent creating new console window on pythonw
        if redirect_out:
            kwargs["creationflags"] = (kwargs.setdefault("creationflags", 0)
                                       | 0x08000000)  # CREATE_NO_WINDOW

        # Avoid closing the above parent and interrupt handles.
        # close_fds is True by default on Python >=3.7
        # or when no stream is captured on Python <3.7
        # (we always capture stdin, so this is already False by default on <3.7)
        kwargs["close_fds"] = False
    else:
        # Create a new session.
        # This makes it easier to interrupt the kernel,
        # because we want to interrupt the whole process group.
        # We don't use setpgrp, which is known to cause problems for kernels starting
        # certain interactive subprocesses, such as bash -i.
        kwargs["start_new_session"] = True
        if not independent:
            env["JPY_PARENT_PID"] = str(os.getpid())

    try:
        proc = Popen(cmd, **kwargs)
    except Exception as exc:
        msg = ("Failed to run command:\n{}\n"
               "    PATH={!r}\n"
               "    with kwargs:\n{!r}\n")
        # exclude environment variables,
        # which may contain access tokens and the like.
        without_env = {
            key: value
            for key, value in kwargs.items() if key != "env"
        }
        msg = msg.format(cmd, env.get("PATH", os.defpath), without_env)
        raise

    if sys.platform == "win32":
        # Attach the interrupt event to the Popen objet so it can be used later.
        proc.win32_interrupt_event = interrupt_event

    # Clean up pipes created to work around Popen bug.
    if redirect_in:
        if stdin is None:
            proc.stdin.close()

    return proc
示例#5
0
def base_launch_kernel(code, fname, stdin=None, stdout=None, stderr=None,
                        executable=None, 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.

    stdin, stdout, stderr : optional (default None)
        Standards streams, as defined in subprocess.Popen.

    fname : unicode, optional
        The JSON connector file, containing ip/port/hmac key information.

    key : str, optional
        The Session key used for HMAC authentication.

    executable : str, optional (default sys.executable)
        The Python executable to use for the kernel process.

    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, shell_port, iopub_port, stdin_port, hb_port)
    where kernel_process is a Popen object and the ports are integers.
    """
    
    # Build the kernel launch command.
    if executable is None:
        executable = sys.executable
    arguments = [ executable, '-c', code, '-f', fname ]
    arguments.extend(extra_arguments)

    # Popen will fail (sometimes with a deadlock) if stdin, stdout, and stderr
    # are invalid. Unfortunately, there is in general no way to detect whether
    # they are valid.  The following two blocks redirect them to (temporary)
    # pipes in certain important cases.

    # If this process has been backgrounded, our stdin is invalid. Since there
    # is no compelling reason for the kernel to inherit our stdin anyway, we'll
    # place this one safe and always redirect.
    redirect_in = True
    _stdin = PIPE if stdin is None else stdin

    # If this process in running on pythonw, we know that stdin, stdout, and
    # stderr are all invalid.
    redirect_out = sys.executable.endswith('pythonw.exe')
    if redirect_out:
        _stdout = PIPE if stdout is None else stdout
        _stderr = PIPE if stderr is None else stderr
    else:
        _stdout, _stderr = stdout, stderr

    # Spawn a kernel.
    if sys.platform == 'win32':
        # Create a Win32 event for interrupting the kernel.
        interrupt_event = ParentPollerWindows.create_interrupt_event()
        arguments += [ '--interrupt=%i'%interrupt_event ]

        # If the kernel is running on pythonw and stdout/stderr are not been
        # re-directed, it will crash when 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.
        # A cleaner solution to this problem would be to pass os.devnull to
        # Popen directly. Unfortunately, that does not work.
        if executable.endswith('pythonw.exe'):
            if stdout is None:
                arguments.append('--no-stdout')
            if stderr is None:
                arguments.append('--no-stderr')

        # Launch the kernel process.
        if independent:
            proc = Popen(arguments,
                         creationflags=512, # CREATE_NEW_PROCESS_GROUP
                         stdin=_stdin, stdout=_stdout, stderr=_stderr)
        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=%i'%int(handle)],
                         stdin=_stdin, stdout=_stdout, stderr=_stderr)

        # Attach the interrupt event to the Popen objet so it can be used later.
        proc.win32_interrupt_event = interrupt_event

    else:
        if independent:
            proc = Popen(arguments, preexec_fn=lambda: os.setsid(),
                         stdin=_stdin, stdout=_stdout, stderr=_stderr)
        else:
            proc = Popen(arguments + ['--parent=1'],
                         stdin=_stdin, stdout=_stdout, stderr=_stderr)

    # Clean up pipes created to work around Popen bug.
    if redirect_in:
        if stdin is None:
            proc.stdin.close()
    if redirect_out:
        if stdout is None:
            proc.stdout.close()
        if stderr is None:
            proc.stderr.close()

    return proc
示例#6
0
def launch_kernel(cmd, stdin=None, stdout=None, stderr=None, independent=False, cwd=None, ipython_kernel=True, **kw):
    """ Launches a localhost kernel, binding to the specified ports.

    Parameters
    ----------
    cmd : Popen list,
        A string of Python code that imports and executes a kernel entry point.

    stdin, stdout, stderr : optional (default None)
        Standards streams, as defined in subprocess.Popen.

    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.

    cwd : path, optional
        The working dir of the kernel process (default: cwd of this process).

    ipython_kernel : bool, optional
        Whether the kernel is an official IPython one,
        and should get a bit of special treatment.

    Returns
    -------

    Popen instance for the kernel subprocess
    """

    # Popen will fail (sometimes with a deadlock) if stdin, stdout, and stderr
    # are invalid. Unfortunately, there is in general no way to detect whether
    # they are valid.  The following two blocks redirect them to (temporary)
    # pipes in certain important cases.

    # If this process has been backgrounded, our stdin is invalid. Since there
    # is no compelling reason for the kernel to inherit our stdin anyway, we'll
    # place this one safe and always redirect.
    redirect_in = True
    _stdin = PIPE if stdin is None else stdin

    # If this process in running on pythonw, we know that stdin, stdout, and
    # stderr are all invalid.
    redirect_out = sys.executable.endswith("pythonw.exe")
    if redirect_out:
        _stdout = PIPE if stdout is None else stdout
        _stderr = PIPE if stderr is None else stderr
    else:
        _stdout, _stderr = stdout, stderr

    encoding = getdefaultencoding(prefer_stream=False)

    # Spawn a kernel.
    if sys.platform == "win32":
        # Popen on Python 2 on Windows cannot handle unicode args or cwd
        cmd = [cast_bytes_py2(c, encoding) for c in cmd]
        if cwd:
            cwd = cast_bytes_py2(cwd, sys.getfilesystemencoding() or "ascii")

        from IPython.kernel.zmq.parentpoller import ParentPollerWindows

        # Create a Win32 event for interrupting the kernel.
        interrupt_event = ParentPollerWindows.create_interrupt_event()
        if ipython_kernel:
            cmd += ["--interrupt=%i" % interrupt_event]

            # If the kernel is running on pythonw and stdout/stderr are not been
            # re-directed, it will crash when 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.
            # A cleaner solution to this problem would be to pass os.devnull to
            # Popen directly. Unfortunately, that does not work.
            if cmd[0].endswith("pythonw.exe"):
                if stdout is None:
                    cmd.append("--no-stdout")
                if stderr is None:
                    cmd.append("--no-stderr")

        # Launch the kernel process.
        if independent:
            proc = Popen(
                cmd,
                creationflags=512,  # CREATE_NEW_PROCESS_GROUP
                stdin=_stdin,
                stdout=_stdout,
                stderr=_stderr,
                env=os.environ,
            )
        else:
            if ipython_kernel:
                try:
                    from _winapi import DuplicateHandle, GetCurrentProcess, DUPLICATE_SAME_ACCESS
                except:
                    from _subprocess import DuplicateHandle, GetCurrentProcess, DUPLICATE_SAME_ACCESS
                pid = GetCurrentProcess()
                handle = DuplicateHandle(pid, pid, pid, 0, True, DUPLICATE_SAME_ACCESS)  # Inheritable by new processes.
                cmd += ["--parent=%i" % handle]

            proc = Popen(cmd, stdin=_stdin, stdout=_stdout, stderr=_stderr, cwd=cwd, env=os.environ)

        # Attach the interrupt event to the Popen objet so it can be used
        # later.
        proc.win32_interrupt_event = interrupt_event

    else:
        if independent:
            proc = Popen(
                cmd,
                preexec_fn=lambda: os.setsid(),
                stdin=_stdin,
                stdout=_stdout,
                stderr=_stderr,
                cwd=cwd,
                env=os.environ,
            )
        else:
            if ipython_kernel:
                cmd += ["--parent=1"]
            proc = Popen(cmd, stdin=_stdin, stdout=_stdout, stderr=_stderr, cwd=cwd, env=os.environ)

    # Clean up pipes created to work around Popen bug.
    if redirect_in:
        if stdin is None:
            proc.stdin.close()
    if redirect_out:
        if stdout is None:
            proc.stdout.close()
        if stderr is None:
            proc.stderr.close()

    return proc
示例#7
0
def launch_kernel(cmd, stdin=None, stdout=None, stderr=None, env=None,
                  independent=False,
                  cwd=None,
                  **kw
                  ):
    """ Launches a localhost kernel, binding to the specified ports.

    Parameters
    ----------
    cmd : Popen list,
        A string of Python code that imports and executes a kernel entry point.

    stdin, stdout, stderr : optional (default None)
        Standards streams, as defined in subprocess.Popen.

    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.

    cwd : path, optional
        The working dir of the kernel process (default: cwd of this process).

    Returns
    -------

    Popen instance for the kernel subprocess
    """

    # Popen will fail (sometimes with a deadlock) if stdin, stdout, and stderr
    # are invalid. Unfortunately, there is in general no way to detect whether
    # they are valid.  The following two blocks redirect them to (temporary)
    # pipes in certain important cases.

    # If this process has been backgrounded, our stdin is invalid. Since there
    # is no compelling reason for the kernel to inherit our stdin anyway, we'll
    # place this one safe and always redirect.
    redirect_in = True
    _stdin = PIPE if stdin is None else stdin

    # If this process in running on pythonw, we know that stdin, stdout, and
    # stderr are all invalid.
    redirect_out = sys.executable.endswith('pythonw.exe')
    if redirect_out:
        blackhole = open(os.devnull, 'w')
        _stdout = blackhole if stdout is None else stdout
        _stderr = blackhole if stderr is None else stderr
    else:
        _stdout, _stderr = stdout, stderr

    env = env if (env is not None) else os.environ.copy()

    encoding = getdefaultencoding(prefer_stream=False)
    kwargs = dict(
        stdin=_stdin,
        stdout=_stdout,
        stderr=_stderr,
        cwd=cwd,
        env=env,
    )

    # Spawn a kernel.
    if sys.platform == 'win32':
        # Popen on Python 2 on Windows cannot handle unicode args or cwd
        cmd = [cast_bytes_py2(c, encoding) for c in cmd]
        if cwd:
            cwd = cast_bytes_py2(cwd, sys.getfilesystemencoding() or 'ascii')
            kwargs['cwd'] = cwd

        from IPython.kernel.zmq.parentpoller import ParentPollerWindows
        # Create a Win32 event for interrupting the kernel
        # and store it in an environment variable.
        interrupt_event = ParentPollerWindows.create_interrupt_event()
        env["JPY_INTERRUPT_EVENT"] = str(interrupt_event)
        # deprecated old env name:
        env["IPY_INTERRUPT_EVENT"] = env["JPY_INTERRUPT_EVENT"]

        try:
            from _winapi import DuplicateHandle, GetCurrentProcess, \
                DUPLICATE_SAME_ACCESS, CREATE_NEW_PROCESS_GROUP
        except:
            from _subprocess import DuplicateHandle, GetCurrentProcess, \
                DUPLICATE_SAME_ACCESS, CREATE_NEW_PROCESS_GROUP
        # Launch the kernel process
        if independent:
            kwargs['creationflags'] = CREATE_NEW_PROCESS_GROUP
        else:
            pid = GetCurrentProcess()
            handle = DuplicateHandle(pid, pid, pid, 0,
                                     True,  # Inheritable by new processes.
                                     DUPLICATE_SAME_ACCESS)
            env['JPY_PARENT_PID'] = str(int(handle))

        proc = Popen(cmd, **kwargs)

        # Attach the interrupt event to the Popen objet so it can be used
        # later.
        proc.win32_interrupt_event = interrupt_event

    else:
        if independent:
            kwargs['preexec_fn'] = lambda: os.setsid()
        else:
            env['JPY_PARENT_PID'] = str(os.getpid())

        proc = Popen(cmd, **kwargs)

    # Clean up pipes created to work around Popen bug.
    if redirect_in:
        if stdin is None:
            proc.stdin.close()

    return proc
示例#8
0
def base_launch_kernel(code,
                       shell_port=0,
                       iopub_port=0,
                       stdin_port=0,
                       hb_port=0,
                       ip=None,
                       stdin=None,
                       stdout=None,
                       stderr=None,
                       executable=None,
                       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.

    shell_port : int, optional
        The port to use for XREP channel.

    iopub_port : int, optional
        The port to use for the SUB channel.

    stdin_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.

    ip  : str, optional
        The ip address the kernel will bind to.

    stdin, stdout, stderr : optional (default None)
        Standards streams, as defined in subprocess.Popen.

    executable : str, optional (default sys.executable)
        The Python executable to use for the kernel process.

    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, shell_port, iopub_port, stdin_port, hb_port)
    where kernel_process is a Popen object and the ports are integers.
    """
    # Find open ports as necessary.
    ports = []
    ports_needed = int(shell_port <= 0) + int(iopub_port <= 0) + \
                   int(stdin_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 shell_port <= 0:
        shell_port = ports.pop(0)
    if iopub_port <= 0:
        iopub_port = ports.pop(0)
    if stdin_port <= 0:
        stdin_port = ports.pop(0)
    if hb_port <= 0:
        hb_port = ports.pop(0)

    # Build the kernel launch command.
    if executable is None:
        executable = sys.executable
    arguments = [
        executable, '-c', code,
        '--shell=%i' % shell_port,
        '--iopub=%i' % iopub_port,
        '--stdin=%i' % stdin_port,
        '--hb=%i' % hb_port
    ]
    if ip is not None:
        arguments.append('--ip=%s' % ip)
    arguments.extend(extra_arguments)

    # Spawn a kernel.
    if sys.platform == 'win32':
        # Create a Win32 event for interrupting the kernel.
        interrupt_event = ParentPollerWindows.create_interrupt_event()
        arguments += ['--interrupt=%i' % interrupt_event]

        # If this process in running on 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.
        if sys.executable.endswith('pythonw.exe'):
            redirect = True
            _stdin = PIPE if stdin is None else stdin
            _stdout = PIPE if stdout is None else stdout
            _stderr = PIPE if stderr is None else stderr
        else:
            redirect = False
            _stdin, _stdout, _stderr = stdin, stdout, stderr

        # If the kernel is running on pythonw and stdout/stderr are not been
        # re-directed, it will crash when 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.
        # A cleaner solution to this problem would be to pass os.devnull to
        # Popen directly. Unfortunately, that does not work.
        if executable.endswith('pythonw.exe'):
            if stdout is None:
                arguments.append('--no-stdout')
            if stderr is None:
                arguments.append('--no-stderr')

        # Launch the kernel process.
        if independent:
            proc = Popen(
                arguments,
                creationflags=512,  # CREATE_NEW_PROCESS_GROUP
                stdin=_stdin,
                stdout=_stdout,
                stderr=_stderr)
        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=%i' % int(handle)],
                         stdin=_stdin,
                         stdout=_stdout,
                         stderr=_stderr)

        # Attach the interrupt event to the Popen objet so it can be used later.
        proc.win32_interrupt_event = interrupt_event

        # Clean up pipes created to work around Popen bug.
        if redirect:
            if stdin is None:
                proc.stdin.close()
            if stdout is None:
                proc.stdout.close()
            if stderr is None:
                proc.stderr.close()

    else:
        if independent:
            proc = Popen(arguments,
                         preexec_fn=lambda: os.setsid(),
                         stdin=stdin,
                         stdout=stdout,
                         stderr=stderr)
        else:
            proc = Popen(arguments + ['--parent=1'],
                         stdin=stdin,
                         stdout=stdout,
                         stderr=stderr)
    return proc, shell_port, iopub_port, stdin_port, hb_port
示例#9
0
def launch_kernel(cmd, stdin=None, stdout=None, stderr=None, env=None,
                        independent=False,
                        cwd=None, ipython_kernel=True,
                        **kw
                        ):
    """ Launches a localhost kernel, binding to the specified ports.

    Parameters
    ----------
    cmd : Popen list,
        A string of Python code that imports and executes a kernel entry point.

    stdin, stdout, stderr : optional (default None)
        Standards streams, as defined in subprocess.Popen.

    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.

    cwd : path, optional
        The working dir of the kernel process (default: cwd of this process).

    ipython_kernel : bool, optional
        Whether the kernel is an official IPython one,
        and should get a bit of special treatment.

    Returns
    -------
    
    Popen instance for the kernel subprocess
    """

    # Popen will fail (sometimes with a deadlock) if stdin, stdout, and stderr
    # are invalid. Unfortunately, there is in general no way to detect whether
    # they are valid.  The following two blocks redirect them to (temporary)
    # pipes in certain important cases.

    # If this process has been backgrounded, our stdin is invalid. Since there
    # is no compelling reason for the kernel to inherit our stdin anyway, we'll
    # place this one safe and always redirect.
    redirect_in = True
    _stdin = PIPE if stdin is None else stdin

    # If this process in running on pythonw, we know that stdin, stdout, and
    # stderr are all invalid.
    redirect_out = sys.executable.endswith('pythonw.exe')
    if redirect_out:
        _stdout = PIPE if stdout is None else stdout
        _stderr = PIPE if stderr is None else stderr
    else:
        _stdout, _stderr = stdout, stderr
    
    env = env if (env is not None) else os.environ.copy()

    encoding = getdefaultencoding(prefer_stream=False)
    
    # Spawn a kernel.
    if sys.platform == 'win32':
        # Popen on Python 2 on Windows cannot handle unicode args or cwd
        cmd = [ cast_bytes_py2(c, encoding) for c in cmd ]
        if cwd:
            cwd = cast_bytes_py2(cwd, sys.getfilesystemencoding() or 'ascii')
        
        from IPython.kernel.zmq.parentpoller import ParentPollerWindows
        # Create a Win32 event for interrupting the kernel.
        interrupt_event = ParentPollerWindows.create_interrupt_event()
        # Store this in an environment variable for third party kernels, but at
        # present, our own kernel expects this as a command line argument.
        env["IPY_INTERRUPT_EVENT"] = str(interrupt_event)
        if ipython_kernel:
            cmd += [ '--interrupt=%i' % interrupt_event ]

            # If the kernel is running on pythonw and stdout/stderr are not been
            # re-directed, it will crash when 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.
            # A cleaner solution to this problem would be to pass os.devnull to
            # Popen directly. Unfortunately, that does not work.
            if cmd[0].endswith('pythonw.exe'):
                if stdout is None:
                    cmd.append('--no-stdout')
                if stderr is None:
                    cmd.append('--no-stderr')

        # Launch the kernel process.
        if independent:
            proc = Popen(cmd,
                         creationflags=512, # CREATE_NEW_PROCESS_GROUP
                         stdin=_stdin, stdout=_stdout, stderr=_stderr, env=env)
        else:
            if ipython_kernel:
                try:
                    from _winapi import DuplicateHandle, GetCurrentProcess, \
                        DUPLICATE_SAME_ACCESS
                except:
                    from _subprocess import DuplicateHandle, GetCurrentProcess, \
                        DUPLICATE_SAME_ACCESS
                pid = GetCurrentProcess()
                handle = DuplicateHandle(pid, pid, pid, 0,
                                         True, # Inheritable by new processes.
                                         DUPLICATE_SAME_ACCESS)
                cmd +=[ '--parent=%i' % handle ]
            
            
            proc = Popen(cmd,
                         stdin=_stdin, stdout=_stdout, stderr=_stderr, cwd=cwd, env=env)

        # Attach the interrupt event to the Popen objet so it can be used later.
        proc.win32_interrupt_event = interrupt_event

    else:
        if independent:
            proc = Popen(cmd, preexec_fn=lambda: os.setsid(),
                         stdin=_stdin, stdout=_stdout, stderr=_stderr, cwd=cwd, env=env)
        else:
            if ipython_kernel:
                cmd += ['--parent=1']
            proc = Popen(cmd,
                         stdin=_stdin, stdout=_stdout, stderr=_stderr, cwd=cwd, env=env)

    # Clean up pipes created to work around Popen bug.
    if redirect_in:
        if stdin is None:
            proc.stdin.close()
    if redirect_out:
        if stdout is None:
            proc.stdout.close()
        if stderr is None:
            proc.stderr.close()

    return proc
示例#10
0
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':
        # Create a Win32 event for interrupting the kernel.
        interrupt_event = ParentPollerWindows.create_interrupt_event()
        arguments += ['--interrupt', str(int(interrupt_event))]

        # 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(
                arguments,
                creationflags=512,  # CREATE_NEW_PROCESS_GROUP
                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)

        # Attach the interrupt event to the Popen objet so it can be used later.
        proc.win32_interrupt_event = interrupt_event

        # 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
示例#11
0
def launch_kernel(cmd, stdin=None, stdout=None, stderr=None, env=None,
                  independent=False, cwd=None, **kw):
    """ Launches a localhost kernel, binding to the specified ports.

    Parameters
    ----------
    cmd : Popen list,
        A string of Python code that imports and executes a kernel entry point.

    stdin, stdout, stderr : optional (default None)
        Standards streams, as defined in subprocess.Popen.

    env: dict, optional
        Environment variables passed to the kernel

    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.

    cwd : path, optional
        The working dir of the kernel process (default: cwd of this process).

    **kw: optional
        Additional arguments for Popen

    Returns
    -------

    Popen instance for the kernel subprocess
    """

    # Popen will fail (sometimes with a deadlock) if stdin, stdout, and stderr
    # are invalid. Unfortunately, there is in general no way to detect whether
    # they are valid.  The following two blocks redirect them to (temporary)
    # pipes in certain important cases.

    # If this process has been backgrounded, our stdin is invalid. Since there
    # is no compelling reason for the kernel to inherit our stdin anyway, we'll
    # place this one safe and always redirect.
    redirect_in = True
    _stdin = PIPE if stdin is None else stdin

    # If this process in running on pythonw, we know that stdin, stdout, and
    # stderr are all invalid.
    redirect_out = sys.executable.endswith('pythonw.exe')
    if redirect_out:
        blackhole = open(os.devnull, 'w')
        _stdout = blackhole if stdout is None else stdout
        _stderr = blackhole if stderr is None else stderr
    else:
        _stdout, _stderr = stdout, stderr

    env = env if (env is not None) else os.environ.copy()

    encoding = getdefaultencoding(prefer_stream=False)
    kwargs = kw.copy()
    main_args = dict(
        stdin=_stdin,
        stdout=_stdout,
        stderr=_stderr,
        cwd=cwd,
        env=env,
    )
    kwargs.update(main_args)

    # Spawn a kernel.
    if sys.platform == 'win32':
        # Popen on Python 2 on Windows cannot handle unicode args or cwd
        cmd = [ cast_bytes_py2(c, encoding) for c in cmd ]
        if cwd:
            cwd = cast_bytes_py2(cwd, sys.getfilesystemencoding() or 'ascii')
            kwargs['cwd'] = cwd

        from .win_interrupt import create_interrupt_event
        # Create a Win32 event for interrupting the kernel
        # and store it in an environment variable.
        interrupt_event = create_interrupt_event()
        env["JPY_INTERRUPT_EVENT"] = str(interrupt_event)
        # deprecated old env name:
        env["IPY_INTERRUPT_EVENT"] = env["JPY_INTERRUPT_EVENT"]

        try:
            from _winapi import DuplicateHandle, GetCurrentProcess, \
                DUPLICATE_SAME_ACCESS, CREATE_NEW_PROCESS_GROUP
        except:
            from _subprocess import DuplicateHandle, GetCurrentProcess, \
                DUPLICATE_SAME_ACCESS, CREATE_NEW_PROCESS_GROUP

        # create a handle on the parent to be inherited
        if independent:
            kwargs['creationflags'] = CREATE_NEW_PROCESS_GROUP
        else:
            pid = GetCurrentProcess()
            handle = DuplicateHandle(pid, pid, pid, 0,
                                     True, # Inheritable by new processes.
                                     DUPLICATE_SAME_ACCESS)
            env['JPY_PARENT_PID'] = str(int(handle))

        # Prevent creating new console window on pythonw
        if redirect_out:
            kwargs['creationflags'] = kwargs.setdefault('creationflags', 0) | 0x08000000 # CREATE_NO_WINDOW

        # Avoid closing the above parent and interrupt handles.
        # close_fds is True by default on Python >=3.7
        # or when no stream is captured on Python <3.7
        # (we always capture stdin, so this is already False by default on <3.7)
        kwargs['close_fds'] = False
    else:
        # Create a new session.
        # This makes it easier to interrupt the kernel,
        # because we want to interrupt the whole process group.
        # We don't use setpgrp, which is known to cause problems for kernels starting
        # certain interactive subprocesses, such as bash -i.
        if PY3:
            kwargs['start_new_session'] = True
        else:
            kwargs['preexec_fn'] = lambda: os.setsid()
        if not independent:
            env['JPY_PARENT_PID'] = str(os.getpid())

    try:
        proc = Popen(cmd, **kwargs)
    except Exception as exc:
        msg = (
            "Failed to run command:\n{}\n"
            "    PATH={!r}\n"
            "    with kwargs:\n{!r}\n"
        )
        # exclude environment variables,
        # which may contain access tokens and the like.
        without_env = {key:value for key, value in kwargs.items() if key != 'env'}
        msg = msg.format(cmd, env.get('PATH', os.defpath), without_env)
        get_logger().error(msg)
        raise

    if sys.platform == 'win32':
        # Attach the interrupt event to the Popen objet so it can be used later.
        proc.win32_interrupt_event = interrupt_event

    # Clean up pipes created to work around Popen bug.
    if redirect_in:
        if stdin is None:
            proc.stdin.close()

    return proc
示例#12
0
def base_launch_kernel(code, xrep_port=0, pub_port=0, req_port=0, hb_port=0,
                       stdin=None, stdout=None, stderr=None,
                       executable=None, 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.

    stdin, stdout, stderr : optional (default None)
        Standards streams, as defined in subprocess.Popen.

    executable : str, optional (default sys.executable)
        The Python executable to use for the kernel process.

    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.
    if executable is None:
        executable = sys.executable
    arguments = [ 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':
        # Create a Win32 event for interrupting the kernel.
        interrupt_event = ParentPollerWindows.create_interrupt_event()
        arguments += [ '--interrupt', str(int(interrupt_event)) ]

        # If this process in running on 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.
        if sys.executable.endswith('pythonw.exe'):
            redirect = True
            _stdin = PIPE if stdin is None else stdin
            _stdout = PIPE if stdout is None else stdout
            _stderr = PIPE if stderr is None else stderr
        else:
            redirect = False
            _stdin, _stdout, _stderr = stdin, stdout, stderr

        # If the kernel is running on pythonw and stdout/stderr are not been
        # re-directed, it will crash when 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.
        # A cleaner solution to this problem would be to pass os.devnull to
        # Popen directly. Unfortunately, that does not work.
        if executable.endswith('pythonw.exe'):
            if stdout is None:
                arguments.append('--no-stdout')
            if stderr is None:
                arguments.append('--no-stderr')

        # Launch the kernel process.
        if independent:
            proc = Popen(arguments, 
                         creationflags=512, # CREATE_NEW_PROCESS_GROUP
                         stdin=_stdin, stdout=_stdout, stderr=_stderr)
        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))],
                         stdin=_stdin, stdout=_stdout, stderr=_stderr)

        # Attach the interrupt event to the Popen objet so it can be used later.
        proc.win32_interrupt_event = interrupt_event

        # Clean up pipes created to work around Popen bug.
        if redirect:
            if stdin is None:
                proc.stdin.close()
            if stdout is None:
                proc.stdout.close()
            if stderr is None:
                proc.stderr.close()

    else:
        if independent:
            proc = Popen(arguments, preexec_fn=lambda: os.setsid(),
                         stdin=stdin, stdout=stdout, stderr=stderr)
        else:
            proc = Popen(arguments + ['--parent'],
                         stdin=stdin, stdout=stdout, stderr=stderr)

    return proc, xrep_port, pub_port, req_port, hb_port