/usr/share/pyshared/pytools/prefork.py is in python-pytools 2011.5-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 | """OpenMPI, once intialized, prohibits forking. This helper module
allows the forking of *one* helper child process before OpenMPI
initializaton that can do the forking for the fork-challenged
parent process.
Since none of this is MPI-specific, it got parked in pytools.
"""
class ExecError(OSError):
pass
class DirectForker:
@staticmethod
def call(cmdline, cwd=None):
from subprocess import call
try:
return call(cmdline, cwd=cwd)
except OSError, e:
raise ExecError("error invoking '%s': %s"
% ( " ".join(cmdline), e))
@staticmethod
def call_capture_stdout(cmdline, cwd=None):
from subprocess import Popen, PIPE
try:
return Popen(cmdline, cwd=cwd, stdin=PIPE, stdout=PIPE, stderr=PIPE).communicate()[0]
except OSError, e:
raise ExecError("error invoking '%s': %s"
% ( " ".join(cmdline), e))
@staticmethod
def call_capture_output(cmdline, cwd=None, error_on_nonzero=True):
"""
:returns: a tuple (return code, stdout_data, stderr_data).
"""
from subprocess import Popen, PIPE
try:
popen = Popen(cmdline, cwd=cwd, stdin=PIPE, stdout=PIPE, stderr=PIPE)
stdout_data, stderr_data = popen.communicate()
if error_on_nonzero and popen.returncode:
raise ExecError("status %d invoking '%s': %s"
% (popen.returncode, " ".join(cmdline), stderr_data))
return popen.returncode, stdout_data, stderr_data
except OSError, e:
raise ExecError("error invoking '%s': %s"
% ( " ".join(cmdline), e))
def _send_packet(sock, data):
from struct import pack
from cPickle import dumps
packet = dumps(data)
sock.sendall(pack("I", len(packet)))
sock.sendall(packet)
def _recv_packet(sock, who="Process", partner="other end"):
from struct import calcsize, unpack
size_bytes_size = calcsize("I")
size_bytes = sock.recv(size_bytes_size)
if len(size_bytes) < size_bytes_size:
from warnings import warn
warn("%s exiting upon apparent death of %"
% (who, partner))
raise SystemExit
size, = unpack("I", size_bytes)
packet = ""
while len(packet) < size:
packet += sock.recv(size)
from cPickle import loads
return loads(packet)
def _fork_server(sock):
import signal
# ignore keyboard interrupts, we'll get notified by the parent.
signal.signal(signal.SIGINT, signal.SIG_IGN)
quitflag = [False]
def quit():
quitflag[0] = True
funcs = {
"quit": quit,
"call": DirectForker.call,
"call_capture_stdout": DirectForker.call_capture_stdout,
"call_capture_output": DirectForker.call_capture_output,
}
try:
while not quitflag[0]:
func_name, args, kwargs = _recv_packet(sock,
who="Prefork server", partner="parent")
try:
result = funcs[func_name](*args, **kwargs)
except Exception, e:
_send_packet(sock, ("exception", e))
else:
_send_packet(sock, ("ok", result))
finally:
sock.close()
import os
os._exit(0)
class IndirectForker:
def __init__(self, server_pid, sock):
self.server_pid = server_pid
self.socket = sock
def _remote_invoke(self, name, *args, **kwargs):
_send_packet(self.socket, (name, args, kwargs))
status, result = _recv_packet(self.socket,
who="Prefork client", partner="prefork server")
if status == "exception":
raise result
elif status == "ok":
return result
def _quit(self):
self._remote_invoke("quit")
from os import waitpid
waitpid(self.server_pid, 0)
def call(self, cmdline, cwd=None):
return self._remote_invoke("call", cmdline, cwd)
def call_capture_stdout(self, cmdline, cwd=None):
return self._remote_invoke("call_capture_stdout", cmdline, cwd)
def call_capture_output(self, cmdline, cwd=None, error_on_nonzero=True):
return self._remote_invoke("call_capture_output", cmdline, cwd,
error_on_nonzero)
def enable_prefork():
if isinstance(forker[0], IndirectForker):
return
from socket import socketpair
s_parent, s_child = socketpair()
from os import fork
fork_res = fork()
if fork_res == 0:
# child
s_parent.close()
_fork_server(s_child)
else:
s_child.close()
forker[0] = IndirectForker(fork_res, s_parent)
import atexit
atexit.register(forker[0]._quit)
forker = [DirectForker()]
def call(cmdline, cwd=None):
return forker[0].call(cmdline, cwd)
def call_capture_stdout(cmdline, cwd=None):
from warnings import warn
warn("call_capture_stdout is deprecated: use call_capture_output instead",
stacklevel=2)
return forker[0].call_capture_stdout(cmdline, cwd)
def call_capture_output(cmdline, cwd=None, error_on_nonzero=True):
return forker[0].call_capture_output(cmdline, cwd, error_on_nonzero)
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