Start webbrowser in a thread. Prevents lockup with Chrome.

If a user has Chrome set as their default browser (system-wide or via
the `BROWSER` environment variable), opening the notebook hangs
because the chrome call doesn't return immediately.  This solves the
issue by opening the browser in a thread.

Note that there remains an issue where killing the notebook will kill
Chrome if the Chrome session was started by us.  I haven't found a way
to work around that despite attempts by making the webbrowser.open()
call in a subprocess.

IPython/frontend/html/notebook/notebookapp.py

@@ -1,315 +1,322 b''
 """A tornado based IPython notebook server.
 
 Authors:
 
 * Brian Granger
 """
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2008-2011  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
+# stdlib
 import errno
 import logging
 import os
 import signal
 import socket
 import sys
+import threading
 import webbrowser
 
+# Third party
 import zmq
 
 # Install the pyzmq ioloop. This has to be done before anything else from
 # tornado is imported.
 from zmq.eventloop import ioloop
 import tornado.ioloop
 tornado.ioloop.IOLoop = ioloop.IOLoop
 
 from tornado import httpserver
 from tornado import web
 
+# Our own libraries
 from .kernelmanager import MappingKernelManager
 from .handlers import (LoginHandler,
     ProjectDashboardHandler, NewHandler, NamedNotebookHandler,
     MainKernelHandler, KernelHandler, KernelActionHandler, IOPubHandler,
     ShellHandler, NotebookRootHandler, NotebookHandler, RSTHandler
 )
 from .notebookmanager import NotebookManager
 
 from IPython.core.application import BaseIPythonApplication
 from IPython.core.profiledir import ProfileDir
 from IPython.zmq.session import Session, default_secure
 from IPython.zmq.zmqshell import ZMQInteractiveShell
 from IPython.zmq.ipkernel import (
     flags as ipkernel_flags,
     aliases as ipkernel_aliases,
     IPKernelApp
 )
 from IPython.utils.traitlets import Dict, Unicode, Int, List, Enum, Bool
 
 #-----------------------------------------------------------------------------
 # Module globals
 #-----------------------------------------------------------------------------
 
 _kernel_id_regex = r"(?P<kernel_id>\w+-\w+-\w+-\w+-\w+)"
 _kernel_action_regex = r"(?P<action>restart|interrupt)"
 _notebook_id_regex = r"(?P<notebook_id>\w+-\w+-\w+-\w+-\w+)"
 
 LOCALHOST = '127.0.0.1'
 
 _examples = """
 ipython notebook                       # start the notebook
 ipython notebook --profile=sympy       # use the sympy profile
 ipython notebook --pylab=inline        # pylab in inline plotting mode
 ipython notebook --certfile=mycert.pem # use SSL/TLS certificate
 ipython notebook --port=5555 --ip=*    # Listen on port 5555, all interfaces
 """
 
 #-----------------------------------------------------------------------------
 # The Tornado web application
 #-----------------------------------------------------------------------------
 
 class NotebookWebApplication(web.Application):
 
     def __init__(self, ipython_app, kernel_manager, notebook_manager, log):
         handlers = [
             (r"/", ProjectDashboardHandler),
             (r"/login", LoginHandler),
             (r"/new", NewHandler),
             (r"/%s" % _notebook_id_regex, NamedNotebookHandler),
             (r"/kernels", MainKernelHandler),
             (r"/kernels/%s" % _kernel_id_regex, KernelHandler),
             (r"/kernels/%s/%s" % (_kernel_id_regex, _kernel_action_regex), KernelActionHandler),
             (r"/kernels/%s/iopub" % _kernel_id_regex, IOPubHandler),
             (r"/kernels/%s/shell" % _kernel_id_regex, ShellHandler),
             (r"/notebooks", NotebookRootHandler),
             (r"/notebooks/%s" % _notebook_id_regex, NotebookHandler),
             (r"/rstservice/render", RSTHandler)
         ]
         settings = dict(
             template_path=os.path.join(os.path.dirname(__file__), "templates"),
             static_path=os.path.join(os.path.dirname(__file__), "static"),
             cookie_secret=os.urandom(1024),
             login_url="/login",
         )
         web.Application.__init__(self, handlers, **settings)
 
         self.kernel_manager = kernel_manager
         self.log = log
         self.notebook_manager = notebook_manager
         self.ipython_app = ipython_app
 
 
 #-----------------------------------------------------------------------------
 # Aliases and Flags
 #-----------------------------------------------------------------------------
 
 flags = dict(ipkernel_flags)
 flags['no-browser']=(
     {'NotebookApp' : {'open_browser' : False}},
     "Don't open the notebook in a browser after startup."
 )
 
 # the flags that are specific to the frontend
 # these must be scrubbed before being passed to the kernel,
 # or it will raise an error on unrecognized flags
 notebook_flags = ['no-browser']
 
 aliases = dict(ipkernel_aliases)
 
 aliases.update({
     'ip': 'NotebookApp.ip',
     'port': 'NotebookApp.port',
     'keyfile': 'NotebookApp.keyfile',
     'certfile': 'NotebookApp.certfile',
     'ws-hostname': 'NotebookApp.ws_hostname',
     'notebook-dir': 'NotebookManager.notebook_dir',
 })
 
 # remove ipkernel flags that are singletons, and don't make sense in
 # multi-kernel evironment:
 aliases.pop('f', None)
 
 notebook_aliases = [u'port', u'ip', u'keyfile', u'certfile', u'ws-hostname',
                     u'notebook-dir']
 
 #-----------------------------------------------------------------------------
 # NotebookApp
 #-----------------------------------------------------------------------------
 
 class NotebookApp(BaseIPythonApplication):
 
     name = 'ipython-notebook'
     default_config_file_name='ipython_notebook_config.py'
     
     description = """
         The IPython HTML Notebook.
         
         This launches a Tornado based HTML Notebook Server that serves up an
         HTML5/Javascript Notebook client.
     """
     examples = _examples
     
     classes = [IPKernelApp, ZMQInteractiveShell, ProfileDir, Session,
                MappingKernelManager, NotebookManager]
     flags = Dict(flags)
     aliases = Dict(aliases)
 
     kernel_argv = List(Unicode)
 
     log_level = Enum((0,10,20,30,40,50,'DEBUG','INFO','WARN','ERROR','CRITICAL'),
                     default_value=logging.INFO,
                     config=True,
                     help="Set the log level by value or name.")
 
     # Network related information.
 
     ip = Unicode(LOCALHOST, config=True,
         help="The IP address the notebook server will listen on."
     )
 
     def _ip_changed(self, name, old, new):
         if new == u'*': self.ip = u''
 
     port = Int(8888, config=True,
         help="The port the notebook server will listen on."
     )
 
     ws_hostname = Unicode(LOCALHOST, config=True,
         help="""The FQDN or IP for WebSocket connections. The default will work
                 fine when the server is listening on localhost, but this needs to
                 be set if the ip option is used. It will be used as the hostname part
                 of the WebSocket url: ws://hostname/path."""
     )
 
     certfile = Unicode(u'', config=True, 
         help="""The full path to an SSL/TLS certificate file."""
     )
     
     keyfile = Unicode(u'', config=True, 
         help="""The full path to a private key file for usage with SSL/TLS."""
     )
 
     password = Unicode(u'', config=True,
                       help="""Password to use for web authentication"""
     )
     
     open_browser = Bool(True, config=True,
                         help="Whether to open in a browser after starting.")
 
     def get_ws_url(self):
         """Return the WebSocket URL for this server."""
         if self.certfile:
             prefix = u'wss://'
         else:
             prefix = u'ws://'
         return prefix + self.ws_hostname + u':' + unicode(self.port)
 
     def parse_command_line(self, argv=None):
         super(NotebookApp, self).parse_command_line(argv)
         if argv is None:
             argv = sys.argv[1:]
 
         self.kernel_argv = list(argv) # copy
         # Kernel should inherit default config file from frontend
         self.kernel_argv.append("--KernelApp.parent_appname='%s'"%self.name)
         # Scrub frontend-specific flags
         for a in argv:
             if a.startswith('-') and a.lstrip('-') in notebook_flags:
                 self.kernel_argv.remove(a)
         swallow_next = False
         for a in argv:
             if swallow_next:
                 self.kernel_argv.remove(a)
                 swallow_next = False
                 continue
             if a.startswith('-'):
                 split = a.lstrip('-').split('=')
                 alias = split[0]
                 if alias in notebook_aliases:
                     self.kernel_argv.remove(a)
                     if len(split) == 1:
                         # alias passed with arg via space
                         swallow_next = True
 
     def init_configurables(self):
         # Don't let Qt or ZMQ swallow KeyboardInterupts.
         signal.signal(signal.SIGINT, signal.SIG_DFL)
 
         # force Session default to be secure
         default_secure(self.config)
         # Create a KernelManager and start a kernel.
         self.kernel_manager = MappingKernelManager(
             config=self.config, log=self.log, kernel_argv=self.kernel_argv,
             connection_dir = self.profile_dir.security_dir,
         )
         self.notebook_manager = NotebookManager(config=self.config, log=self.log)
         self.notebook_manager.list_notebooks()
 
     def init_logging(self):
         super(NotebookApp, self).init_logging()
         # This prevents double log messages because tornado use a root logger that
         # self.log is a child of. The logging module dipatches log messages to a log
         # and all of its ancenstors until propagate is set to False.
         self.log.propagate = False
 
     def initialize(self, argv=None):
         super(NotebookApp, self).initialize(argv)
         self.init_configurables()
         self.web_app = NotebookWebApplication(
             self, self.kernel_manager, self.notebook_manager, self.log
         )
         if self.certfile:
             ssl_options = dict(certfile=self.certfile)
             if self.keyfile:
                 ssl_options['keyfile'] = self.keyfile
         else:
             ssl_options = None
         self.web_app.password = self.password
         self.http_server = httpserver.HTTPServer(self.web_app, ssl_options=ssl_options)
         if ssl_options is None and not self.ip:
             self.log.critical('WARNING: the notebook server is listening on all IP addresses '
                               'but not using any encryption or authentication. This is highly '
                               'insecure and not recommended.')
 
         # Try random ports centered around the default.
         from random import randint
         n = 50  # Max number of attempts, keep reasonably large.
         for port in [self.port] + [self.port + randint(-2*n, 2*n) for i in range(n)]:
             try:
                 self.http_server.listen(port, self.ip)
             except socket.error, e:
                 if e.errno != errno.EADDRINUSE:
                     raise
                 self.log.info('The port %i is already in use, trying another random port.' % port)
             else:
                 self.port = port
                 break
 
     def start(self):
         ip = self.ip if self.ip else '[all ip addresses on your system]'
         proto = 'https' if self.certfile else 'http'
         self.log.info("The IPython Notebook is running at: %s://%s:%i" % (proto,
                                                                           ip,
                                                                           self.port))
         if self.open_browser:
             ip = self.ip or '127.0.0.1'
-            webbrowser.open("%s://%s:%i" % (proto, ip, self.port), new=2)
+            b = lambda : webbrowser.open("%s://%s:%i" % (proto, ip, self.port),
+                                         new=2)
+            threading.Thread(target=b).start()
+
         ioloop.IOLoop.instance().start()
 
 #-----------------------------------------------------------------------------
 # Main entry point
 #-----------------------------------------------------------------------------
 
 def launch_new_instance():
     app = NotebookApp()
     app.initialize()
     app.start()