handle potentially absent win32api in launcher.py

IPython/parallel/apps/launcher.py

@@ -1,971 +1,972 b''
 #!/usr/bin/env python
 # encoding: utf-8
 """
 Facilities for launching IPython processes asynchronously.
 """
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2008-2009  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
 #-----------------------------------------------------------------------------
 
 import copy
 import logging
 import os
 import re
 import stat
 
 from signal import SIGINT, SIGTERM
 try:
     from signal import SIGKILL
 except ImportError:
     SIGKILL=SIGTERM
 
 from subprocess import Popen, PIPE, STDOUT
 try:
     from subprocess import check_output
 except ImportError:
     # pre-2.7, define check_output with Popen
     def check_output(*args, **kwargs):
         kwargs.update(dict(stdout=PIPE))
         p = Popen(*args, **kwargs)
         out,err = p.communicate()
         return out
 
 from zmq.eventloop import ioloop
 
 from IPython.external import Itpl
 # from IPython.config.configurable import Configurable
 from IPython.utils.traitlets import Any, Str, Int, List, Unicode, Dict, Instance, CUnicode
 from IPython.utils.path import get_ipython_module_path
 from IPython.utils.process import find_cmd, pycmd2argv, FindCmdError
 
 from IPython.parallel.factory import LoggingFactory
 
 # load winhpcjob only on Windows
 try:
     from .winhpcjob import (
         IPControllerTask, IPEngineTask,
         IPControllerJob, IPEngineSetJob
     )
 except ImportError:
     pass
 
 
 #-----------------------------------------------------------------------------
 # Paths to the kernel apps
 #-----------------------------------------------------------------------------
 
 
 ipcluster_cmd_argv = pycmd2argv(get_ipython_module_path(
     'IPython.parallel.apps.ipclusterapp'
 ))
 
 ipengine_cmd_argv = pycmd2argv(get_ipython_module_path(
     'IPython.parallel.apps.ipengineapp'
 ))
 
 ipcontroller_cmd_argv = pycmd2argv(get_ipython_module_path(
     'IPython.parallel.apps.ipcontrollerapp'
 ))
 
 #-----------------------------------------------------------------------------
 # Base launchers and errors
 #-----------------------------------------------------------------------------
 
 
 class LauncherError(Exception):
     pass
 
 
 class ProcessStateError(LauncherError):
     pass
 
 
 class UnknownStatus(LauncherError):
     pass
 
 
 class BaseLauncher(LoggingFactory):
     """An asbtraction for starting, stopping and signaling a process."""
 
     # In all of the launchers, the work_dir is where child processes will be
     # run. This will usually be the cluster_dir, but may not be. any work_dir
     # passed into the __init__ method will override the config value.
     # This should not be used to set the work_dir for the actual engine
     # and controller. Instead, use their own config files or the
     # controller_args, engine_args attributes of the launchers to add
     # the --work-dir option.
     work_dir = Unicode(u'.')
     loop = Instance('zmq.eventloop.ioloop.IOLoop')
     
     start_data = Any()
     stop_data = Any()
     
     def _loop_default(self):
         return ioloop.IOLoop.instance()
 
     def __init__(self, work_dir=u'.', config=None, **kwargs):
         super(BaseLauncher, self).__init__(work_dir=work_dir, config=config, **kwargs)
         self.state = 'before' # can be before, running, after
         self.stop_callbacks = []
         self.start_data = None
         self.stop_data = None
 
     @property
     def args(self):
         """A list of cmd and args that will be used to start the process.
 
         This is what is passed to :func:`spawnProcess` and the first element
         will be the process name.
         """
         return self.find_args()
 
     def find_args(self):
         """The ``.args`` property calls this to find the args list.
 
         Subcommand should implement this to construct the cmd and args.
         """
         raise NotImplementedError('find_args must be implemented in a subclass')
 
     @property
     def arg_str(self):
         """The string form of the program arguments."""
         return ' '.join(self.args)
 
     @property
     def running(self):
         """Am I running."""
         if self.state == 'running':
             return True
         else:
             return False
 
     def start(self):
         """Start the process.
 
         This must return a deferred that fires with information about the
         process starting (like a pid, job id, etc.).
         """
         raise NotImplementedError('start must be implemented in a subclass')
 
     def stop(self):
         """Stop the process and notify observers of stopping.
 
         This must return a deferred that fires with information about the
         processing stopping, like errors that occur while the process is
         attempting to be shut down. This deferred won't fire when the process
         actually stops. To observe the actual process stopping, see
         :func:`observe_stop`.
         """
         raise NotImplementedError('stop must be implemented in a subclass')
 
     def on_stop(self, f):
         """Get a deferred that will fire when the process stops.
 
         The deferred will fire with data that contains information about
         the exit status of the process.
         """
         if self.state=='after':
             return f(self.stop_data)
         else:
             self.stop_callbacks.append(f)
 
     def notify_start(self, data):
         """Call this to trigger startup actions.
 
         This logs the process startup and sets the state to 'running'.  It is
         a pass-through so it can be used as a callback.
         """
 
         self.log.info('Process %r started: %r' % (self.args[0], data))
         self.start_data = data
         self.state = 'running'
         return data
 
     def notify_stop(self, data):
         """Call this to trigger process stop actions.
 
         This logs the process stopping and sets the state to 'after'. Call
         this to trigger all the deferreds from :func:`observe_stop`."""
 
         self.log.info('Process %r stopped: %r' % (self.args[0], data))
         self.stop_data = data
         self.state = 'after'
         for i in range(len(self.stop_callbacks)):
             d = self.stop_callbacks.pop()
             d(data)
         return data
 
     def signal(self, sig):
         """Signal the process.
 
         Return a semi-meaningless deferred after signaling the process.
 
         Parameters
         ----------
         sig : str or int
             'KILL', 'INT', etc., or any signal number
         """
         raise NotImplementedError('signal must be implemented in a subclass')
 
 
 #-----------------------------------------------------------------------------
 # Local process launchers
 #-----------------------------------------------------------------------------
 
 
 class LocalProcessLauncher(BaseLauncher):
     """Start and stop an external process in an asynchronous manner.
 
     This will launch the external process with a working directory of
     ``self.work_dir``.
     """
 
     # This is used to to construct self.args, which is passed to 
     # spawnProcess.
     cmd_and_args = List([])
     poll_frequency = Int(100) # in ms
 
     def __init__(self, work_dir=u'.', config=None, **kwargs):
         super(LocalProcessLauncher, self).__init__(
             work_dir=work_dir, config=config, **kwargs
         )
         self.process = None
         self.start_deferred = None
         self.poller = None
 
     def find_args(self):
         return self.cmd_and_args
 
     def start(self):
         if self.state == 'before':
             self.process = Popen(self.args,
                 stdout=PIPE,stderr=PIPE,stdin=PIPE,
                 env=os.environ,
                 cwd=self.work_dir
             )
             
             self.loop.add_handler(self.process.stdout.fileno(), self.handle_stdout, self.loop.READ)
             self.loop.add_handler(self.process.stderr.fileno(), self.handle_stderr, self.loop.READ)
             self.poller = ioloop.PeriodicCallback(self.poll, self.poll_frequency, self.loop)
             self.poller.start()
             self.notify_start(self.process.pid)
         else:
             s = 'The process was already started and has state: %r' % self.state
             raise ProcessStateError(s)
 
     def stop(self):
         return self.interrupt_then_kill()
 
     def signal(self, sig):
         if self.state == 'running':
             self.process.send_signal(sig)
 
     def interrupt_then_kill(self, delay=2.0):
         """Send INT, wait a delay and then send KILL."""
         self.signal(SIGINT)
         self.killer  = ioloop.DelayedCallback(lambda : self.signal(SIGKILL), delay*1000, self.loop)
         self.killer.start()
 
     # callbacks, etc:
     
     def handle_stdout(self, fd, events):
         line = self.process.stdout.readline()
         # a stopped process will be readable but return empty strings
         if line:
             self.log.info(line[:-1])
         else:
             self.poll()
     
     def handle_stderr(self, fd, events):
         line = self.process.stderr.readline()
         # a stopped process will be readable but return empty strings
         if line:
             self.log.error(line[:-1])
         else:
             self.poll()
     
     def poll(self):
         status = self.process.poll()
         if status is not None:
             self.poller.stop()
             self.loop.remove_handler(self.process.stdout.fileno())
             self.loop.remove_handler(self.process.stderr.fileno())
             self.notify_stop(dict(exit_code=status, pid=self.process.pid))
         return status
 
 class LocalControllerLauncher(LocalProcessLauncher):
     """Launch a controller as a regular external process."""
 
     controller_cmd = List(ipcontroller_cmd_argv, config=True)
     # Command line arguments to ipcontroller.
     controller_args = List(['--log-to-file','--log-level', str(logging.INFO)], config=True)
 
     def find_args(self):
         return self.controller_cmd + self.controller_args
 
     def start(self, cluster_dir):
         """Start the controller by cluster_dir."""
         self.controller_args.extend(['--cluster-dir', cluster_dir])
         self.cluster_dir = unicode(cluster_dir)
         self.log.info("Starting LocalControllerLauncher: %r" % self.args)
         return super(LocalControllerLauncher, self).start()
 
 
 class LocalEngineLauncher(LocalProcessLauncher):
     """Launch a single engine as a regular externall process."""
 
     engine_cmd = List(ipengine_cmd_argv, config=True)
     # Command line arguments for ipengine.
     engine_args = List(
         ['--log-to-file','--log-level', str(logging.INFO)], config=True
     )
 
     def find_args(self):
         return self.engine_cmd + self.engine_args
 
     def start(self, cluster_dir):
         """Start the engine by cluster_dir."""
         self.engine_args.extend(['--cluster-dir', cluster_dir])
         self.cluster_dir = unicode(cluster_dir)
         return super(LocalEngineLauncher, self).start()
 
 
 class LocalEngineSetLauncher(BaseLauncher):
     """Launch a set of engines as regular external processes."""
 
     # Command line arguments for ipengine.
     engine_args = List(
         ['--log-to-file','--log-level', str(logging.INFO)], config=True
     )
     # launcher class
     launcher_class = LocalEngineLauncher
     
     launchers = Dict()
     stop_data = Dict()
     
     def __init__(self, work_dir=u'.', config=None, **kwargs):
         super(LocalEngineSetLauncher, self).__init__(
             work_dir=work_dir, config=config, **kwargs
         )
         self.stop_data = {}
 
     def start(self, n, cluster_dir):
         """Start n engines by profile or cluster_dir."""
         self.cluster_dir = unicode(cluster_dir)
         dlist = []
         for i in range(n):
             el = self.launcher_class(work_dir=self.work_dir, config=self.config, logname=self.log.name)
             # Copy the engine args over to each engine launcher.
             el.engine_args = copy.deepcopy(self.engine_args)
             el.on_stop(self._notice_engine_stopped)
             d = el.start(cluster_dir)
             if i==0:
                 self.log.info("Starting LocalEngineSetLauncher: %r" % el.args)
             self.launchers[i] = el
             dlist.append(d)
         self.notify_start(dlist)
         # The consumeErrors here could be dangerous
         # dfinal = gatherBoth(dlist, consumeErrors=True)
         # dfinal.addCallback(self.notify_start)
         return dlist
 
     def find_args(self):
         return ['engine set']
 
     def signal(self, sig):
         dlist = []
         for el in self.launchers.itervalues():
             d = el.signal(sig)
             dlist.append(d)
         # dfinal = gatherBoth(dlist, consumeErrors=True)
         return dlist
 
     def interrupt_then_kill(self, delay=1.0):
         dlist = []
         for el in self.launchers.itervalues():
             d = el.interrupt_then_kill(delay)
             dlist.append(d)
         # dfinal = gatherBoth(dlist, consumeErrors=True)
         return dlist
 
     def stop(self):
         return self.interrupt_then_kill()
     
     def _notice_engine_stopped(self, data):
         pid = data['pid']
         for idx,el in self.launchers.iteritems():
             if el.process.pid == pid:
                 break
         self.launchers.pop(idx)
         self.stop_data[idx] = data
         if not self.launchers:
             self.notify_stop(self.stop_data)
 
 
 #-----------------------------------------------------------------------------
 # MPIExec launchers
 #-----------------------------------------------------------------------------
 
 
 class MPIExecLauncher(LocalProcessLauncher):
     """Launch an external process using mpiexec."""
 
     # The mpiexec command to use in starting the process.
     mpi_cmd = List(['mpiexec'], config=True)
     # The command line arguments to pass to mpiexec.
     mpi_args = List([], config=True)
     # The program to start using mpiexec.
     program = List(['date'], config=True)
     # The command line argument to the program.
     program_args = List([], config=True)
     # The number of instances of the program to start.
     n = Int(1, config=True)
 
     def find_args(self):
         """Build self.args using all the fields."""
         return self.mpi_cmd + ['-n', str(self.n)] + self.mpi_args + \
                self.program + self.program_args
 
     def start(self, n):
         """Start n instances of the program using mpiexec."""
         self.n = n
         return super(MPIExecLauncher, self).start()
 
 
 class MPIExecControllerLauncher(MPIExecLauncher):
     """Launch a controller using mpiexec."""
 
     controller_cmd = List(ipcontroller_cmd_argv, config=True)
     # Command line arguments to ipcontroller.
     controller_args = List(['--log-to-file','--log-level', str(logging.INFO)], config=True)
     n = Int(1, config=False)
 
     def start(self, cluster_dir):
         """Start the controller by cluster_dir."""
         self.controller_args.extend(['--cluster-dir', cluster_dir])
         self.cluster_dir = unicode(cluster_dir)
         self.log.info("Starting MPIExecControllerLauncher: %r" % self.args)
         return super(MPIExecControllerLauncher, self).start(1)
 
     def find_args(self):
         return self.mpi_cmd + ['-n', self.n] + self.mpi_args + \
                self.controller_cmd + self.controller_args
 
 
 class MPIExecEngineSetLauncher(MPIExecLauncher):
 
     program = List(ipengine_cmd_argv, config=True)
     # Command line arguments for ipengine.
     program_args = List(
         ['--log-to-file','--log-level', str(logging.INFO)], config=True
     )
     n = Int(1, config=True)
 
     def start(self, n, cluster_dir):
         """Start n engines by profile or cluster_dir."""
         self.program_args.extend(['--cluster-dir', cluster_dir])
         self.cluster_dir = unicode(cluster_dir)
         self.n = n
         self.log.info('Starting MPIExecEngineSetLauncher: %r' % self.args)
         return super(MPIExecEngineSetLauncher, self).start(n)
 
 #-----------------------------------------------------------------------------
 # SSH launchers
 #-----------------------------------------------------------------------------
 
 # TODO: Get SSH Launcher working again.
 
 class SSHLauncher(LocalProcessLauncher):
     """A minimal launcher for ssh.
 
     To be useful this will probably have to be extended to use the ``sshx``
     idea for environment variables.  There could be other things this needs
     as well.
     """
 
     ssh_cmd = List(['ssh'], config=True)
     ssh_args = List(['-tt'], config=True)
     program = List(['date'], config=True)
     program_args = List([], config=True)
     hostname = CUnicode('', config=True)
     user = CUnicode('', config=True)
     location = CUnicode('')
 
     def _hostname_changed(self, name, old, new):
         if self.user:
             self.location = u'%s@%s' % (self.user, new)
         else:
             self.location = new
 
     def _user_changed(self, name, old, new):
         self.location = u'%s@%s' % (new, self.hostname)
 
     def find_args(self):
         return self.ssh_cmd + self.ssh_args + [self.location] + \
                self.program + self.program_args
 
     def start(self, cluster_dir, hostname=None, user=None):
         self.cluster_dir = unicode(cluster_dir)
         if hostname is not None:
             self.hostname = hostname
         if user is not None:
             self.user = user
         
         return super(SSHLauncher, self).start()
     
     def signal(self, sig):
         if self.state == 'running':
             # send escaped ssh connection-closer
             self.process.stdin.write('~.')
             self.process.stdin.flush()
         
 
 
 class SSHControllerLauncher(SSHLauncher):
 
     program = List(ipcontroller_cmd_argv, config=True)
     # Command line arguments to ipcontroller.
     program_args = List(['-r', '--log-to-file','--log-level', str(logging.INFO)], config=True)
 
 
 class SSHEngineLauncher(SSHLauncher):
     program = List(ipengine_cmd_argv, config=True)
     # Command line arguments for ipengine.
     program_args = List(
         ['--log-to-file','--log-level', str(logging.INFO)], config=True
     )
     
 class SSHEngineSetLauncher(LocalEngineSetLauncher):
     launcher_class = SSHEngineLauncher
     engines = Dict(config=True)
     
     def start(self, n, cluster_dir):
         """Start engines by profile or cluster_dir.
         `n` is ignored, and the `engines` config property is used instead.
         """
         
         self.cluster_dir = unicode(cluster_dir)
         dlist = []
         for host, n in self.engines.iteritems():
             if isinstance(n, (tuple, list)):
                 n, args = n
             else:
                 args = copy.deepcopy(self.engine_args)
             
             if '@' in host:
                 user,host = host.split('@',1)
             else:
                 user=None
             for i in range(n):
                 el = self.launcher_class(work_dir=self.work_dir, config=self.config, logname=self.log.name)
                 
                 # Copy the engine args over to each engine launcher.
                 i
                 el.program_args = args
                 el.on_stop(self._notice_engine_stopped)
                 d = el.start(cluster_dir, user=user, hostname=host)
                 if i==0:
                     self.log.info("Starting SSHEngineSetLauncher: %r" % el.args)
                 self.launchers[host+str(i)] = el
                 dlist.append(d)
         self.notify_start(dlist)
         return dlist
     
 
 
 #-----------------------------------------------------------------------------
 # Windows HPC Server 2008 scheduler launchers
 #-----------------------------------------------------------------------------
 
 
 # This is only used on Windows.
 def find_job_cmd():
     if os.name=='nt':
         try:
             return find_cmd('job')
-        except FindCmdError:
+        except (FindCmdError, ImportError):
+            # ImportError will be raised if win32api is not installed
             return 'job'
     else:
         return 'job'
 
 
 class WindowsHPCLauncher(BaseLauncher):
 
     # A regular expression used to get the job id from the output of the 
     # submit_command.
     job_id_regexp = Str(r'\d+', config=True)
     # The filename of the instantiated job script.
     job_file_name = CUnicode(u'ipython_job.xml', config=True)
     # The full path to the instantiated job script. This gets made dynamically
     # by combining the work_dir with the job_file_name.
     job_file = CUnicode(u'')
     # The hostname of the scheduler to submit the job to
     scheduler = CUnicode('', config=True)
     job_cmd = CUnicode(find_job_cmd(), config=True)
 
     def __init__(self, work_dir=u'.', config=None, **kwargs):
         super(WindowsHPCLauncher, self).__init__(
             work_dir=work_dir, config=config, **kwargs
         )
 
     @property
     def job_file(self):
         return os.path.join(self.work_dir, self.job_file_name)
 
     def write_job_file(self, n):
         raise NotImplementedError("Implement write_job_file in a subclass.")
 
     def find_args(self):
         return [u'job.exe']
         
     def parse_job_id(self, output):
         """Take the output of the submit command and return the job id."""
         m = re.search(self.job_id_regexp, output)
         if m is not None:
             job_id = m.group()
         else:
             raise LauncherError("Job id couldn't be determined: %s" % output)
         self.job_id = job_id
         self.log.info('Job started with job id: %r' % job_id)
         return job_id
 
     def start(self, n):
         """Start n copies of the process using the Win HPC job scheduler."""
         self.write_job_file(n)
         args = [
             'submit',
             '/jobfile:%s' % self.job_file,
             '/scheduler:%s' % self.scheduler
         ]
         self.log.info("Starting Win HPC Job: %s" % (self.job_cmd + ' ' + ' '.join(args),))
         # Twisted will raise DeprecationWarnings if we try to pass unicode to this
         output = check_output([self.job_cmd]+args,
             env=os.environ,
             cwd=self.work_dir,
             stderr=STDOUT
         )
         job_id = self.parse_job_id(output)
         self.notify_start(job_id)
         return job_id
 
     def stop(self):
         args = [
             'cancel',
             self.job_id,
             '/scheduler:%s' % self.scheduler
         ]
         self.log.info("Stopping Win HPC Job: %s" % (self.job_cmd + ' ' + ' '.join(args),))
         try:
             output = check_output([self.job_cmd]+args,
                 env=os.environ,
                 cwd=self.work_dir,
                 stderr=STDOUT
             )
         except:
             output = 'The job already appears to be stoppped: %r' % self.job_id
         self.notify_stop(dict(job_id=self.job_id, output=output))  # Pass the output of the kill cmd
         return output
 
 
 class WindowsHPCControllerLauncher(WindowsHPCLauncher):
 
     job_file_name = CUnicode(u'ipcontroller_job.xml', config=True)
     extra_args = List([], config=False)
 
     def write_job_file(self, n):
         job = IPControllerJob(config=self.config)
 
         t = IPControllerTask(config=self.config)
         # The tasks work directory is *not* the actual work directory of 
         # the controller. It is used as the base path for the stdout/stderr
         # files that the scheduler redirects to.
         t.work_directory = self.cluster_dir
         # Add the --cluster-dir and from self.start().
         t.controller_args.extend(self.extra_args)
         job.add_task(t)
 
         self.log.info("Writing job description file: %s" % self.job_file)
         job.write(self.job_file)
 
     @property
     def job_file(self):
         return os.path.join(self.cluster_dir, self.job_file_name)
 
     def start(self, cluster_dir):
         """Start the controller by cluster_dir."""
         self.extra_args = ['--cluster-dir', cluster_dir]
         self.cluster_dir = unicode(cluster_dir)
         return super(WindowsHPCControllerLauncher, self).start(1)
 
 
 class WindowsHPCEngineSetLauncher(WindowsHPCLauncher):
 
     job_file_name = CUnicode(u'ipengineset_job.xml', config=True)
     extra_args = List([], config=False)
 
     def write_job_file(self, n):
         job = IPEngineSetJob(config=self.config)
 
         for i in range(n):
             t = IPEngineTask(config=self.config)
             # The tasks work directory is *not* the actual work directory of 
             # the engine. It is used as the base path for the stdout/stderr
             # files that the scheduler redirects to.
             t.work_directory = self.cluster_dir
             # Add the --cluster-dir and from self.start().
             t.engine_args.extend(self.extra_args)
             job.add_task(t)
 
         self.log.info("Writing job description file: %s" % self.job_file)
         job.write(self.job_file)
 
     @property
     def job_file(self):
         return os.path.join(self.cluster_dir, self.job_file_name)
 
     def start(self, n, cluster_dir):
         """Start the controller by cluster_dir."""
         self.extra_args = ['--cluster-dir', cluster_dir]
         self.cluster_dir = unicode(cluster_dir)
         return super(WindowsHPCEngineSetLauncher, self).start(n)
 
 
 #-----------------------------------------------------------------------------
 # Batch (PBS) system launchers
 #-----------------------------------------------------------------------------
 
 class BatchSystemLauncher(BaseLauncher):
     """Launch an external process using a batch system.
 
     This class is designed to work with UNIX batch systems like PBS, LSF,
     GridEngine, etc.  The overall model is that there are different commands
     like qsub, qdel, etc. that handle the starting and stopping of the process.
 
     This class also has the notion of a batch script. The ``batch_template``
     attribute can be set to a string that is a template for the batch script.
     This template is instantiated using Itpl. Thus the template can use
     ${n} fot the number of instances. Subclasses can add additional variables
     to the template dict.
     """
 
     # Subclasses must fill these in.  See PBSEngineSet
     # The name of the command line program used to submit jobs.
     submit_command = List([''], config=True)
     # The name of the command line program used to delete jobs.
     delete_command = List([''], config=True)
     # A regular expression used to get the job id from the output of the 
     # submit_command.
     job_id_regexp = CUnicode('', config=True)
     # The string that is the batch script template itself.
     batch_template = CUnicode('', config=True)
     # The file that contains the batch template
     batch_template_file = CUnicode(u'', config=True)
     # The filename of the instantiated batch script.
     batch_file_name = CUnicode(u'batch_script', config=True)
     # The PBS Queue
     queue = CUnicode(u'', config=True)
     
     # not configurable, override in subclasses
     # PBS Job Array regex
     job_array_regexp = CUnicode('')
     job_array_template = CUnicode('')
     # PBS Queue regex
     queue_regexp = CUnicode('')
     queue_template = CUnicode('')
     # The default batch template, override in subclasses
     default_template = CUnicode('')
     # The full path to the instantiated batch script.
     batch_file = CUnicode(u'')
     # the format dict used with batch_template:
     context = Dict()
 
     
     def find_args(self):
         return self.submit_command + [self.batch_file]
     
     def __init__(self, work_dir=u'.', config=None, **kwargs):
         super(BatchSystemLauncher, self).__init__(
             work_dir=work_dir, config=config, **kwargs
         )
         self.batch_file = os.path.join(self.work_dir, self.batch_file_name)
 
     def parse_job_id(self, output):
         """Take the output of the submit command and return the job id."""
         m = re.search(self.job_id_regexp, output)
         if m is not None:
             job_id = m.group()
         else:
             raise LauncherError("Job id couldn't be determined: %s" % output)
         self.job_id = job_id
         self.log.info('Job submitted with job id: %r' % job_id)
         return job_id
 
     def write_batch_script(self, n):
         """Instantiate and write the batch script to the work_dir."""
         self.context['n'] = n
         self.context['queue'] = self.queue
         print self.context
         # first priority is batch_template if set
         if self.batch_template_file and not self.batch_template:
             # second priority is batch_template_file
             with open(self.batch_template_file) as f:
                 self.batch_template = f.read()
         if not self.batch_template:
             # third (last) priority is default_template
             self.batch_template = self.default_template
         
         regex = re.compile(self.job_array_regexp)
         # print regex.search(self.batch_template)
         if not regex.search(self.batch_template):
             self.log.info("adding job array settings to batch script")
             firstline, rest = self.batch_template.split('\n',1)
             self.batch_template = u'\n'.join([firstline, self.job_array_template, rest])
         
         regex = re.compile(self.queue_regexp)
         # print regex.search(self.batch_template)
         if self.queue and not regex.search(self.batch_template):
             self.log.info("adding PBS queue settings to batch script")
             firstline, rest = self.batch_template.split('\n',1)
             self.batch_template = u'\n'.join([firstline, self.queue_template, rest])
             
         script_as_string = Itpl.itplns(self.batch_template, self.context)
         self.log.info('Writing instantiated batch script: %s' % self.batch_file)
     
         with open(self.batch_file, 'w') as f:
             f.write(script_as_string)
         os.chmod(self.batch_file, stat.S_IRUSR | stat.S_IWUSR | stat.S_IXUSR)
 
     def start(self, n, cluster_dir):
         """Start n copies of the process using a batch system."""
         # Here we save profile and cluster_dir in the context so they
         # can be used in the batch script template as ${profile} and
         # ${cluster_dir}
         self.context['cluster_dir'] = cluster_dir
         self.cluster_dir = unicode(cluster_dir)
         self.write_batch_script(n)
         output = check_output(self.args, env=os.environ)
         
         job_id = self.parse_job_id(output)
         self.notify_start(job_id)
         return job_id
 
     def stop(self):
         output = check_output(self.delete_command+[self.job_id], env=os.environ)
         self.notify_stop(dict(job_id=self.job_id, output=output)) # Pass the output of the kill cmd
         return output
 
 
 class PBSLauncher(BatchSystemLauncher):
     """A BatchSystemLauncher subclass for PBS."""
 
     submit_command = List(['qsub'], config=True)
     delete_command = List(['qdel'], config=True)
     job_id_regexp = CUnicode(r'\d+', config=True)
     
     batch_file = CUnicode(u'')
     job_array_regexp = CUnicode('#PBS\W+-t\W+[\w\d\-\$]+')
     job_array_template = CUnicode('#PBS -t 1-$n')
     queue_regexp = CUnicode('#PBS\W+-q\W+\$?\w+')
     queue_template = CUnicode('#PBS -q $queue')
 
 
 class PBSControllerLauncher(PBSLauncher):
     """Launch a controller using PBS."""
 
     batch_file_name = CUnicode(u'pbs_controller', config=True)
     default_template= CUnicode("""#!/bin/sh
 #PBS -V
 #PBS -N ipcontroller
 %s --log-to-file --cluster-dir $cluster_dir
 """%(' '.join(ipcontroller_cmd_argv)))
 
     def start(self, cluster_dir):
         """Start the controller by profile or cluster_dir."""
         self.log.info("Starting PBSControllerLauncher: %r" % self.args)
         return super(PBSControllerLauncher, self).start(1, cluster_dir)
 
 
 class PBSEngineSetLauncher(PBSLauncher):
     """Launch Engines using PBS"""
     batch_file_name = CUnicode(u'pbs_engines', config=True)
     default_template= CUnicode(u"""#!/bin/sh
 #PBS -V
 #PBS -N ipengine
 %s --cluster-dir $cluster_dir
 """%(' '.join(ipengine_cmd_argv)))
 
     def start(self, n, cluster_dir):
         """Start n engines by profile or cluster_dir."""
         self.log.info('Starting %i engines with PBSEngineSetLauncher: %r' % (n, self.args))
         return super(PBSEngineSetLauncher, self).start(n, cluster_dir)
 
 #SGE is very similar to PBS
 
 class SGELauncher(PBSLauncher):
     """Sun GridEngine is a PBS clone with slightly different syntax"""
     job_array_regexp = CUnicode('#$$\W+-t\W+[\w\d\-\$]+')
     job_array_template = CUnicode('#$$ -t 1-$n')
     queue_regexp = CUnicode('#$$\W+-q\W+\$?\w+')
     queue_template = CUnicode('#$$ -q $queue')
 
 class SGEControllerLauncher(SGELauncher):
     """Launch a controller using SGE."""
 
     batch_file_name = CUnicode(u'sge_controller', config=True)
     default_template= CUnicode(u"""#$$ -V
 #$$ -S /bin/sh
 #$$ -N ipcontroller
 %s --log-to-file --cluster-dir $cluster_dir
 """%(' '.join(ipcontroller_cmd_argv)))
 
     def start(self, cluster_dir):
         """Start the controller by profile or cluster_dir."""
         self.log.info("Starting PBSControllerLauncher: %r" % self.args)
         return super(PBSControllerLauncher, self).start(1, cluster_dir)
 
 class SGEEngineSetLauncher(SGELauncher):
     """Launch Engines with SGE"""
     batch_file_name = CUnicode(u'sge_engines', config=True)
     default_template = CUnicode("""#$$ -V
 #$$ -S /bin/sh
 #$$ -N ipengine
 %s --cluster-dir $cluster_dir
 """%(' '.join(ipengine_cmd_argv)))
 
     def start(self, n, cluster_dir):
         """Start n engines by profile or cluster_dir."""
         self.log.info('Starting %i engines with SGEEngineSetLauncher: %r' % (n, self.args))
         return super(SGEEngineSetLauncher, self).start(n, cluster_dir)
 
 
 #-----------------------------------------------------------------------------
 # A launcher for ipcluster itself!
 #-----------------------------------------------------------------------------
 
 
 class IPClusterLauncher(LocalProcessLauncher):
     """Launch the ipcluster program in an external process."""
 
     ipcluster_cmd = List(ipcluster_cmd_argv, config=True)
     # Command line arguments to pass to ipcluster.
     ipcluster_args = List(
         ['--clean-logs', '--log-to-file', '--log-level', str(logging.INFO)], config=True)
     ipcluster_subcommand = Str('start')
     ipcluster_n = Int(2)
 
     def find_args(self):
         return self.ipcluster_cmd + [self.ipcluster_subcommand] + \
             ['-n', repr(self.ipcluster_n)] + self.ipcluster_args
 
     def start(self):
         self.log.info("Starting ipcluster: %r" % self.args)
         return super(IPClusterLauncher, self).start()