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
|
#
# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements. See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License. You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
import os
import signal
import socket
import sys
import traceback
import multiprocessing
from ctypes import c_bool
from errno import EINTR, ECHILD
from socket import AF_INET, SOCK_STREAM, SOMAXCONN
from signal import SIGHUP, SIGTERM, SIGCHLD, SIG_DFL, SIG_IGN
from pyspark.worker import main as worker_main
from pyspark.serializers import write_int
try:
POOLSIZE = multiprocessing.cpu_count()
except NotImplementedError:
POOLSIZE = 4
exit_flag = multiprocessing.Value(c_bool, False)
def should_exit():
global exit_flag
return exit_flag.value
def compute_real_exit_code(exit_code):
# SystemExit's code can be integer or string, but os._exit only accepts integers
import numbers
if isinstance(exit_code, numbers.Integral):
return exit_code
else:
return 1
def worker(listen_sock):
# Redirect stdout to stderr
os.dup2(2, 1)
sys.stdout = sys.stderr # The sys.stdout object is different from file descriptor 1
# Manager sends SIGHUP to request termination of workers in the pool
def handle_sighup(*args):
assert should_exit()
signal.signal(SIGHUP, handle_sighup)
# Cleanup zombie children
def handle_sigchld(*args):
pid = status = None
try:
while (pid, status) != (0, 0):
pid, status = os.waitpid(0, os.WNOHANG)
except EnvironmentError as err:
if err.errno == EINTR:
# retry
handle_sigchld()
elif err.errno != ECHILD:
raise
signal.signal(SIGCHLD, handle_sigchld)
# Blocks until the socket is closed by draining the input stream
# until it raises an exception or returns EOF.
def waitSocketClose(sock):
try:
while True:
# Empty string is returned upon EOF (and only then).
if sock.recv(4096) == '':
return
except:
pass
# Handle clients
while not should_exit():
# Wait until a client arrives or we have to exit
sock = None
while not should_exit() and sock is None:
try:
sock, addr = listen_sock.accept()
except EnvironmentError as err:
if err.errno != EINTR:
raise
if sock is not None:
# Fork a child to handle the client.
# The client is handled in the child so that the manager
# never receives SIGCHLD unless a worker crashes.
if os.fork() == 0:
# Leave the worker pool
signal.signal(SIGHUP, SIG_DFL)
signal.signal(SIGCHLD, SIG_DFL)
listen_sock.close()
# Read the socket using fdopen instead of socket.makefile() because the latter
# seems to be very slow; note that we need to dup() the file descriptor because
# otherwise writes also cause a seek that makes us miss data on the read side.
infile = os.fdopen(os.dup(sock.fileno()), "a+", 65536)
outfile = os.fdopen(os.dup(sock.fileno()), "a+", 65536)
exit_code = 0
try:
worker_main(infile, outfile)
except SystemExit as exc:
exit_code = exc.code
finally:
outfile.flush()
# The Scala side will close the socket upon task completion.
waitSocketClose(sock)
os._exit(compute_real_exit_code(exit_code))
else:
sock.close()
def launch_worker(listen_sock):
if os.fork() == 0:
try:
worker(listen_sock)
except Exception as err:
traceback.print_exc()
os._exit(1)
else:
assert should_exit()
os._exit(0)
def manager():
# Create a new process group to corral our children
os.setpgid(0, 0)
# Create a listening socket on the AF_INET loopback interface
listen_sock = socket.socket(AF_INET, SOCK_STREAM)
listen_sock.bind(('127.0.0.1', 0))
listen_sock.listen(max(1024, 2 * POOLSIZE, SOMAXCONN))
listen_host, listen_port = listen_sock.getsockname()
write_int(listen_port, sys.stdout)
# Launch initial worker pool
for idx in range(POOLSIZE):
launch_worker(listen_sock)
listen_sock.close()
def shutdown():
global exit_flag
exit_flag.value = True
# Gracefully exit on SIGTERM, don't die on SIGHUP
signal.signal(SIGTERM, lambda signum, frame: shutdown())
signal.signal(SIGHUP, SIG_IGN)
# Cleanup zombie children
def handle_sigchld(*args):
try:
pid, status = os.waitpid(0, os.WNOHANG)
if status != 0 and not should_exit():
raise RuntimeError("worker crashed: %s, %s" % (pid, status))
except EnvironmentError as err:
if err.errno not in (ECHILD, EINTR):
raise
signal.signal(SIGCHLD, handle_sigchld)
# Initialization complete
sys.stdout.close()
try:
while not should_exit():
try:
# Spark tells us to exit by closing stdin
if os.read(0, 512) == '':
shutdown()
except EnvironmentError as err:
if err.errno != EINTR:
shutdown()
raise
finally:
signal.signal(SIGTERM, SIG_DFL)
exit_flag.value = True
# Send SIGHUP to notify workers of shutdown
os.kill(0, SIGHUP)
if __name__ == '__main__':
manager()
|
