247 lines
8.2 KiB
Python
247 lines
8.2 KiB
Python
#
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# threads.py: anaconda thread management
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#
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# Copyright (C) 2012
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# Red Hat, Inc. All rights reserved.
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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#
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# Author(s): Chris Lumens <clumens@redhat.com>
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#
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import logging
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log = logging.getLogger("anaconda")
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import threading
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_WORKER_THREAD_PREFIX = "AnaWorkerThread"
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class ThreadManager(object):
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"""A singleton class for managing threads and processes.
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Notes:
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THE INSTANCE HAS TO BE CREATED IN THE MAIN THREAD!
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This manager makes one assumption that contradicts python's
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threading module documentation. In this class, we assume that thread
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names are unique and meaningful. This is an okay assumption for us
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to make given that anaconda is only ever going to have a handful of
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special purpose threads.
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"""
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def __init__(self):
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self._objs = {}
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self._objs_lock = threading.RLock()
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self._errors = {}
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self._main_thread = threading.current_thread()
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def __call__(self):
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return self
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def add(self, obj):
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"""Given a Thread or Process object, add it to the list of known objects
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and start it. It is assumed that obj.name is unique and descriptive.
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"""
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# we need to lock the thread dictionary when adding a new thread,
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# so that callers can't get & join threads that are not yet started
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with self._objs_lock:
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if obj.name in self._objs:
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raise KeyError("Cannot add thread '%s', a thread with the same name already running" % obj.name)
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self._objs[obj.name] = obj
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obj.start()
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return obj.name
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def remove(self, name):
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"""Removes a thread from the list of known objects. This should only
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be called when a thread exits, or there will be no way to get a
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handle on it.
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"""
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with self._objs_lock:
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self._objs.pop(name)
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def exists(self, name):
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"""Determine if a thread or process exists with the given name."""
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# thread in the ThreadManager only officially exists once started
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with self._objs_lock:
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return name in self._objs
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def get(self, name):
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"""Given an object name, see if it exists and return the object.
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Return None if no such object exists. Additionally, this method
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will re-raise any uncaught exception in the thread.
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"""
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# without the lock it would be possible to get & join
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# a thread that was not yet started
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with self._objs_lock:
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obj = self._objs.get(name)
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if obj:
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self.raise_if_error(name)
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return obj
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def wait(self, name):
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"""Wait for the thread to exit and if the thread exited with an error
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re-raise it here.
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"""
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# we don't need a lock here,
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# because get() acquires it itself
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try:
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self.get(name).join()
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except AttributeError:
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pass
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# - if there is a thread object for the given name,
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# we join it
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# - if there is not a thread object for the given name,
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# we get None, try to join it, suppress the AttributeError
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# and return immediately
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self.raise_if_error(name)
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def wait_all(self):
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"""Wait for all threads to exit and if there was an error re-raise it.
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"""
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for name in self._objs.keys():
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if self.get(name) == threading.current_thread():
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continue
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log.debug("Waiting for thread %s to exit", name)
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self.wait(name)
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if self.any_errors:
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thread_names = ", ".join(thread_name for thread_name in self._errors.iterkeys()
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if self._errors[thread_name])
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msg = "Unhandled errors from the following threads detected: %s" % thread_names
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raise RuntimeError(msg)
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def set_error(self, name, *exc_info):
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"""Set the error data for a thread
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The exception data is expected to be the tuple from sys.exc_info()
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"""
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self._errors[name] = exc_info
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def get_error(self, name):
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"""Get the error data for a thread using its name
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"""
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return self._errors.get(name)
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@property
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def any_errors(self):
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"""Return True of there have been any errors in any threads
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"""
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return any(self._errors.values())
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def raise_if_error(self, name):
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"""If a thread has failed due to an exception, raise it into the main
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thread and remove it from errors.
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"""
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if name not in self._errors:
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# no errors found for the thread
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return
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exc_info = self._errors.pop(name)
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if exc_info:
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raise exc_info[0], exc_info[1], exc_info[2]
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def in_main_thread(self):
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"""Return True if it is run in the main thread."""
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cur_thread = threading.current_thread()
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return cur_thread is self._main_thread
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@property
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def running(self):
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""" Return the number of running threads.
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:returns: number of running threads
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:rtype: int
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"""
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with self._objs_lock:
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return len(self._objs)
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@property
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def names(self):
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""" Return the names of the running threads.
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:returns: list of thread names
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:rtype: list of strings
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"""
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with self._objs_lock:
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return self._objs.keys()
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class AnacondaThread(threading.Thread):
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"""A threading.Thread subclass that exists only for a couple purposes:
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(1) Make exceptions that happen in a thread invoke our exception handling
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code as well. Otherwise, threads will silently die and we are doing
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a lot of complicated code in them now.
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(2) Remove themselves from the thread manager when completed.
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(3) All created threads are made daemonic, which means anaconda will quit
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when the main process is killed.
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"""
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# class-wide dictionary ensuring unique thread names
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_prefix_thread_counts = dict()
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def __init__(self, *args, **kwargs):
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# if neither name nor prefix is given, use the worker prefix
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if "name" not in kwargs and "prefix" not in kwargs:
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kwargs["prefix"] = _WORKER_THREAD_PREFIX
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# if prefix is specified, use it to construct new thread name
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prefix = kwargs.pop("prefix", None)
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if prefix:
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thread_num = self._prefix_thread_counts.get(prefix, 0) + 1
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self._prefix_thread_counts[prefix] = thread_num
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kwargs["name"] = prefix + str(thread_num)
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if "fatal" in kwargs:
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self._fatal = kwargs.pop("fatal")
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else:
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self._fatal = True
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threading.Thread.__init__(self, *args, **kwargs)
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self.daemon = True
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def run(self, *args, **kwargs):
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# http://bugs.python.org/issue1230540#msg25696
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import sys
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log.info("Running Thread: %s (%s)", self.name, self.ident)
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try:
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threading.Thread.run(self, *args, **kwargs)
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# pylint: disable=bare-except
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except:
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threadMgr.set_error(self.name, *sys.exc_info())
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if self._fatal:
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sys.excepthook(*sys.exc_info())
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finally:
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threadMgr.remove(self.name)
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log.info("Thread Done: %s (%s)", self.name, self.ident)
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def initThreading():
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"""Set up threading for anaconda's use. This method must be called before
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any GTK or threading code is called, or else threads will only run when
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an event is triggered in the GTK main loop. And IT HAS TO BE CALLED IN
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THE MAIN THREAD.
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"""
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global threadMgr
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threadMgr = ThreadManager()
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threadMgr = None
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