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Unified Diff: Lib/multiprocessing/process.py

Issue 2061: Review PEP 371 patch 1 Base URL: http://svn.python.org/view/*checkout*/python/trunk/
Patch Set: Created 15 years, 9 months ago
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Index: Lib/multiprocessing/process.py
===================================================================
--- Lib/multiprocessing/process.py (revision 0)
+++ Lib/multiprocessing/process.py (revision 0)
@@ -0,0 +1,302 @@
+#
+# Module providing the `Process` class which emulates `threading.Thread`
+#
+# multiprocessing/process.py
+#
+# Copyright (c) 2006-2008, R Oudkerk --- see COPYING.txt
+#
+
+__all__ = ['Process', 'current_process', 'active_children']
+
+#
+# Imports
+#
+
+import os
+import sys
+import signal
+import itertools
+
+#
+#
+#
+
+try:
+ ORIGINAL_DIR = os.path.abspath(os.getcwd())
+except OSError:
+ ORIGINAL_DIR = None
+
+try:
+ bytes
+except NameError:
+ bytes = str # XXX not needed in Py2.6 and Py3.0
+
+#
+# Public functions
+#
+
+def current_process():
+ '''
+ Return process object representing the current process
+ '''
+ return _current_process
+
+def active_children():
+ '''
+ Return list of process objects corresponding to live child processes
+ '''
+ _cleanup()
+ return list(_current_process._children)
+
+#
+#
+#
+
+def _cleanup():
+ # check for processes which have finished
+ for p in list(_current_process._children):
+ if p._popen.poll() is not None:
+ _current_process._children.discard(p)
+
+#
+# The `Process` class
+#
+
+class Process(object):
+ '''
+ Process objects represent activity that is run in a separate process
+
+ The class is analagous to `threading.Thread`
+ '''
+ _Popen = None
+
+ def __init__(self, group=None, target=None, name=None, args=(), kwargs={}):
+ assert group is None, 'group argument must be None for now'
+ count = _current_process._counter.next()
+ self._identity = _current_process._identity + (count,)
+ self._authkey = _current_process._authkey
+ self._daemonic = _current_process._daemonic
+ self._tempdir = _current_process._tempdir
+ self._parent_pid = os.getpid()
+ self._popen = None
+ self._target = target
+ self._args = tuple(args)
+ self._kwargs = dict(kwargs)
+ self._name = name or type(self).__name__ + '-' + \
+ ':'.join(str(i) for i in self._identity)
+
+ def run(self):
+ '''
+ Method to be run in sub-process; can be overridden in sub-class
+ '''
+ if self._target:
+ self._target(*self._args, **self._kwargs)
+
+ def start(self):
+ '''
+ Start child process
+ '''
+ assert self._popen is None, 'cannot start a process twice'
+ assert self._parent_pid == os.getpid(), \
+ 'can only start a process object created by current process'
+ assert not _current_process._daemonic, \
+ 'daemonic processes are not allowed to have children'
+ _cleanup()
+ if self._Popen is not None:
+ Popen = self._Popen
+ else:
+ from .forking import Popen
+ self._popen = Popen(self)
+ _current_process._children.add(self)
+
+ def terminate(self):
+ '''
+ Terminate process; sends SIGTERM signal or uses TerminateProcess()
+ '''
+ self._popen.terminate()
+
+ def join(self, timeout=None):
+ '''
+ Wait until child process terminates
+ '''
+ assert self._parent_pid == os.getpid(), 'can only join a child process'
+ assert self._popen is not None, 'can only join a started process'
+ res = self._popen.wait(timeout)
+ if res is not None:
+ _current_process._children.discard(self)
+
+ def is_alive(self):
+ '''
+ Return whether process is alive
+ '''
+ if self is _current_process:
+ return True
+ assert self._parent_pid == os.getpid(), 'can only test a child process'
+ if self._popen is None:
+ return False
+ self._popen.poll()
+ return self._popen.returncode is None
+
+ def get_name(self):
+ '''
+ Return name of process
+ '''
+ return self._name
+
+ def set_name(self, name):
+ '''
+ Set name of process
+ '''
+ assert isinstance(name, str), 'name must be a string'
+ self._name = name
+
+ def is_daemon(self):
+ '''
+ Return whether process is a daemon
+ '''
+ return self._daemonic
+
+ def set_daemon(self, daemonic):
+ '''
+ Set whether process is a daemon
+ '''
+ assert self._popen is None, 'process has already started'
+ self._daemonic = daemonic
+
+ def get_authkey(self):
+ '''
+ Return authorization key of process
+ '''
+ return self._authkey
+
+ def set_authkey(self, authkey):
+ '''
+ Set authorization key of process
+ '''
+ self._authkey = AuthenticationString(authkey)
+
+ def get_exitcode(self):
+ '''
+ Return exit code of process or `None` if it has yet to stop
+ '''
+ if self._popen is None:
+ return self._popen
+ return self._popen.poll()
+
+ def get_ident(self):
+ '''
+ Return indentifier (PID) of process or `None` if it has yet to start
+ '''
+ if self is _current_process:
+ return os.getpid()
+ else:
+ return self._popen and self._popen.pid
+
+ pid = property(get_ident)
+
+ def __repr__(self):
+ if self is _current_process:
+ status = 'started'
+ elif self._parent_pid != os.getpid():
+ status = 'unknown'
+ elif self._popen is None:
+ status = 'initial'
+ else:
+ if self._popen.poll() is not None:
+ status = self.get_exitcode()
+ else:
+ status = 'started'
+
+ if type(status) is int:
+ if status == 0:
+ status = 'stopped'
+ else:
+ status = 'stopped[%s]' % _exitcode_to_name.get(status, status)
+
+ return '<%s(%s, %s%s)>' % (type(self).__name__, self._name,
+ status, self._daemonic and ' daemon' or '')
+
+ ##
+
+ def _bootstrap(self):
+ from . import util
+ global _current_process
+
+ try:
+ self._children = set()
+ self._counter = itertools.count(1)
+ try:
+ os.close(sys.stdin.fileno())
+ except (OSError, ValueError):
+ pass
+ _current_process = self
+ util._finalizer_registry.clear()
+ util._run_after_forkers()
+ util.info('child process calling self.run()')
+ try:
+ self.run()
+ exitcode = 0
+ finally:
+ util._exit_function()
+ except SystemExit, e:
+ if not e.args:
+ exitcode = 1
+ elif type(e.args[0]) is int:
+ exitcode = e.args[0]
+ else:
+ sys.stderr.write(e.args[0] + '\n')
+ sys.stderr.flush()
+ exitcode = 1
+ except:
+ exitcode = 1
+ import traceback
+ sys.stderr.write('Process %s:\n' % self.get_name())
+ sys.stderr.flush()
+ traceback.print_exc()
+
+ util.info('process exiting with exitcode %d' % exitcode)
+ return exitcode
+
+#
+# We subclass bytes to avoid accidental transmission of auth keys over network
+#
+
+class AuthenticationString(bytes):
+ def __reduce__(self):
+ from .forking import Popen
+ if not Popen.thread_is_spawning():
+ raise TypeError(
+ 'Pickling an AuthenticationString object is '
+ 'disallowed for security reasons'
+ )
+ return AuthenticationString, (bytes(self),)
+
+#
+# Create object representing the main process
+#
+
+class _MainProcess(Process):
+
+ def __init__(self):
+ self._identity = ()
+ self._daemonic = False
+ self._name = 'MainProcess'
+ self._parent_pid = None
+ self._popen = None
+ self._counter = itertools.count(1)
+ self._children = set()
+ self._authkey = AuthenticationString(os.urandom(32))
+ self._tempdir = None
+
+_current_process = _MainProcess()
+del _MainProcess
+
+#
+# Give names to some return codes
+#
+
+_exitcode_to_name = {}
+
+for name, signum in signal.__dict__.items():
+ if name[:3]=='SIG' and '_' not in name:
+ _exitcode_to_name[-signum] = name

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