[SPARK-2898] [PySpark] fix bugs in deamon.py
1. do not use signal handler for SIGCHILD, it's easy to cause deadlock 2. handle EINTR during accept() 3. pass errno into JVM 4. handle EAGAIN during fork() Now, it can pass 50k tasks tests in 180 seconds. Author: Davies Liu <davies.liu@gmail.com> Closes #1842 from davies/qa and squashes the following commits: f0ea451 [Davies Liu] fix lint 03a2e8c [Davies Liu] cleanup dead children every seconds 32cb829 [Davies Liu] fix lint 0cd0817 [Davies Liu] fix bugs in deamon.py
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@ -68,7 +68,7 @@ private[spark] class PythonWorkerFactory(pythonExec: String, envVars: Map[String
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val socket = new Socket(daemonHost, daemonPort)
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val pid = new DataInputStream(socket.getInputStream).readInt()
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if (pid < 0) {
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throw new IllegalStateException("Python daemon failed to launch worker")
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throw new IllegalStateException("Python daemon failed to launch worker with code " + pid)
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}
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daemonWorkers.put(socket, pid)
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socket
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@ -22,7 +22,8 @@ import select
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import socket
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import sys
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import traceback
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from errno import EINTR, ECHILD
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import time
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from errno import EINTR, ECHILD, EAGAIN
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from socket import AF_INET, SOCK_STREAM, SOMAXCONN
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from signal import SIGHUP, SIGTERM, SIGCHLD, SIG_DFL, SIG_IGN
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from pyspark.worker import main as worker_main
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@ -80,6 +81,17 @@ def worker(sock):
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os._exit(compute_real_exit_code(exit_code))
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# Cleanup zombie children
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def cleanup_dead_children():
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try:
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while True:
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pid, _ = os.waitpid(0, os.WNOHANG)
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if not pid:
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break
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except:
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pass
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def manager():
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# Create a new process group to corral our children
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os.setpgid(0, 0)
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@ -102,29 +114,21 @@ def manager():
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signal.signal(SIGTERM, handle_sigterm) # Gracefully exit on SIGTERM
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signal.signal(SIGHUP, SIG_IGN) # Don't die on SIGHUP
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# Cleanup zombie children
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def handle_sigchld(*args):
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try:
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pid, status = os.waitpid(0, os.WNOHANG)
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if status != 0:
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msg = "worker %s crashed abruptly with exit status %s" % (pid, status)
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print >> sys.stderr, msg
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except EnvironmentError as err:
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if err.errno not in (ECHILD, EINTR):
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raise
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signal.signal(SIGCHLD, handle_sigchld)
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# Initialization complete
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sys.stdout.close()
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try:
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while True:
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try:
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ready_fds = select.select([0, listen_sock], [], [])[0]
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ready_fds = select.select([0, listen_sock], [], [], 1)[0]
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except select.error as ex:
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if ex[0] == EINTR:
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continue
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else:
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raise
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# cleanup in signal handler will cause deadlock
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cleanup_dead_children()
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if 0 in ready_fds:
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try:
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worker_pid = read_int(sys.stdin)
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@ -137,29 +141,41 @@ def manager():
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pass # process already died
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if listen_sock in ready_fds:
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sock, addr = listen_sock.accept()
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try:
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sock, _ = listen_sock.accept()
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except OSError as e:
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if e.errno == EINTR:
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continue
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raise
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# Launch a worker process
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try:
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pid = os.fork()
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if pid == 0:
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listen_sock.close()
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try:
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worker(sock)
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except:
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traceback.print_exc()
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os._exit(1)
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else:
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os._exit(0)
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else:
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sock.close()
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except OSError as e:
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print >> sys.stderr, "Daemon failed to fork PySpark worker: %s" % e
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outfile = os.fdopen(os.dup(sock.fileno()), "a+", 65536)
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write_int(-1, outfile) # Signal that the fork failed
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outfile.flush()
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outfile.close()
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if e.errno in (EAGAIN, EINTR):
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time.sleep(1)
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pid = os.fork() # error here will shutdown daemon
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else:
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outfile = sock.makefile('w')
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write_int(e.errno, outfile) # Signal that the fork failed
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outfile.flush()
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outfile.close()
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sock.close()
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continue
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if pid == 0:
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# in child process
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listen_sock.close()
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try:
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worker(sock)
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except:
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traceback.print_exc()
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os._exit(1)
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else:
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os._exit(0)
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else:
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sock.close()
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finally:
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shutdown(1)
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