/usr/lib/python3/dist-packages/pytools/prefork.py is in python3-pytools 2016.2.6-1.
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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 | """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.
"""
from __future__ import absolute_import
class ExecError(OSError):
pass
class DirectForker(object):
def __init__(self):
self.apids = {}
self.count = 0
def call(self, cmdline, cwd=None):
from subprocess import call
try:
return call(cmdline, cwd=cwd)
except OSError as e:
raise ExecError("error invoking '%s': %s"
% (" ".join(cmdline), e))
def call_async(self, cmdline, cwd=None):
from subprocess import Popen
try:
self.count += 1
proc = Popen(cmdline, cwd=cwd)
self.apids[self.count] = proc
return self.count
except OSError as e:
raise ExecError("error invoking '%s': %s"
% (" ".join(cmdline), e))
def call_capture_output(self, cmdline, cwd=None, error_on_nonzero=True):
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 as e:
raise ExecError("error invoking '%s': %s"
% (" ".join(cmdline), e))
def wait(self, aid):
proc = self.apids.pop(aid)
retc = proc.wait()
return retc
def waitall(self):
rets = {}
for aid in list(self.apids):
rets[aid] = self.wait(aid)
return rets
def _send_packet(sock, data):
from struct import pack
from six.moves.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 %s" % (who, partner))
raise SystemExit
size, = unpack("I", size_bytes)
packet = b""
while len(packet) < size:
packet += sock.recv(size)
from six.moves.cPickle import loads
return loads(packet)
def _fork_server(sock):
# Ignore keyboard interrupts, we'll get notified by the parent.
import signal
signal.signal(signal.SIGINT, signal.SIG_IGN)
# Construct a local DirectForker to do the dirty work
df = DirectForker()
funcs = {
"call": df.call,
"call_async": df.call_async,
"call_capture_output": df.call_capture_output,
"wait": df.wait,
"waitall": df.waitall
}
try:
while True:
func_name, args, kwargs = _recv_packet(
sock, who="Prefork server", partner="parent"
)
if func_name == "quit":
df.waitall()
_send_packet(sock, ("ok", None))
break
else:
try:
result = funcs[func_name](*args, **kwargs)
except Exception as e:
_send_packet(sock, ("exception", e))
else:
_send_packet(sock, ("ok", result))
finally:
sock.close()
import os
os._exit(0)
class IndirectForker(object):
def __init__(self, server_pid, sock):
self.server_pid = server_pid
self.socket = sock
import atexit
atexit.register(self._quit)
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_async(self, cmdline, cwd=None):
return self._remote_invoke("call_async", 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 wait(self, aid):
return self._remote_invoke("wait", aid)
def waitall(self):
return self._remote_invoke("waitall")
def enable_prefork():
global forker
if isinstance(forker, IndirectForker):
return
from socket import socketpair
s_parent, s_child = socketpair()
from os import fork
fork_res = fork()
# Child
if fork_res == 0:
s_parent.close()
_fork_server(s_child)
# Parent
else:
s_child.close()
forker = IndirectForker(fork_res, s_parent)
forker = DirectForker()
def call(cmdline, cwd=None):
return forker.call(cmdline, cwd)
def call_async(cmdline, cwd=None):
return forker.call_async(cmdline, cwd)
def call_capture_output(cmdline, cwd=None, error_on_nonzero=True):
return forker.call_capture_output(cmdline, cwd, error_on_nonzero)
def wait(aid):
return forker.wait(aid)
def waitall():
return forker.waitall()
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