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#
# 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 atexit
import os
import sys
import signal
import shlex
import platform
from subprocess import Popen, PIPE
from threading import Thread
from py4j.java_gateway import java_import, JavaGateway, GatewayClient
def launch_gateway():
SPARK_HOME = os.environ["SPARK_HOME"]
gateway_port = -1
if "PYSPARK_GATEWAY_PORT" in os.environ:
gateway_port = int(os.environ["PYSPARK_GATEWAY_PORT"])
else:
# Launch the Py4j gateway using Spark's run command so that we pick up the
# proper classpath and settings from spark-env.sh
on_windows = platform.system() == "Windows"
script = "./bin/spark-submit.cmd" if on_windows else "./bin/spark-submit"
submit_args = os.environ.get("PYSPARK_SUBMIT_ARGS")
submit_args = submit_args if submit_args is not None else ""
submit_args = shlex.split(submit_args)
command = [os.path.join(SPARK_HOME, script)] + submit_args + ["pyspark-shell"]
if not on_windows:
# Don't send ctrl-c / SIGINT to the Java gateway:
def preexec_func():
signal.signal(signal.SIGINT, signal.SIG_IGN)
env = dict(os.environ)
env["IS_SUBPROCESS"] = "1" # tell JVM to exit after python exits
proc = Popen(command, stdout=PIPE, stdin=PIPE, preexec_fn=preexec_func, env=env)
else:
# preexec_fn not supported on Windows
proc = Popen(command, stdout=PIPE, stdin=PIPE)
try:
# Determine which ephemeral port the server started on:
gateway_port = proc.stdout.readline()
gateway_port = int(gateway_port)
except ValueError:
# Grab the remaining lines of stdout
(stdout, _) = proc.communicate()
exit_code = proc.poll()
error_msg = "Launching GatewayServer failed"
error_msg += " with exit code %d!\n" % exit_code if exit_code else "!\n"
error_msg += "Warning: Expected GatewayServer to output a port, but found "
if gateway_port == "" and stdout == "":
error_msg += "no output.\n"
else:
error_msg += "the following:\n\n"
error_msg += "--------------------------------------------------------------\n"
error_msg += gateway_port + stdout
error_msg += "--------------------------------------------------------------\n"
raise Exception(error_msg)
# In Windows, ensure the Java child processes do not linger after Python has exited.
# In UNIX-based systems, the child process can kill itself on broken pipe (i.e. when
# the parent process' stdin sends an EOF). In Windows, however, this is not possible
# because java.lang.Process reads directly from the parent process' stdin, contending
# with any opportunity to read an EOF from the parent. Note that this is only best
# effort and will not take effect if the python process is violently terminated.
if on_windows:
# In Windows, the child process here is "spark-submit.cmd", not the JVM itself
# (because the UNIX "exec" command is not available). This means we cannot simply
# call proc.kill(), which kills only the "spark-submit.cmd" process but not the
# JVMs. Instead, we use "taskkill" with the tree-kill option "/t" to terminate all
# child processes in the tree (http://technet.microsoft.com/en-us/library/bb491009.aspx)
def killChild():
Popen(["cmd", "/c", "taskkill", "/f", "/t", "/pid", str(proc.pid)])
atexit.register(killChild)
# Create a thread to echo output from the GatewayServer, which is required
# for Java log output to show up:
class EchoOutputThread(Thread):
def __init__(self, stream):
Thread.__init__(self)
self.daemon = True
self.stream = stream
def run(self):
while True:
line = self.stream.readline()
sys.stderr.write(line)
EchoOutputThread(proc.stdout).start()
# Connect to the gateway
gateway = JavaGateway(GatewayClient(port=gateway_port), auto_convert=False)
# Import the classes used by PySpark
java_import(gateway.jvm, "org.apache.spark.SparkConf")
java_import(gateway.jvm, "org.apache.spark.api.java.*")
java_import(gateway.jvm, "org.apache.spark.api.python.*")
java_import(gateway.jvm, "org.apache.spark.mllib.api.python.*")
java_import(gateway.jvm, "org.apache.spark.sql.SQLContext")
java_import(gateway.jvm, "org.apache.spark.sql.hive.HiveContext")
java_import(gateway.jvm, "org.apache.spark.sql.hive.LocalHiveContext")
java_import(gateway.jvm, "org.apache.spark.sql.hive.TestHiveContext")
java_import(gateway.jvm, "scala.Tuple2")
return gateway
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