[SPARK-4897] [PySpark] Python 3 support

This PR update PySpark to support Python 3 (tested with 3.4).

Known issue: unpickle array from Pyrolite is broken in Python 3, those tests are skipped.

TODO: ec2/spark-ec2.py is not fully tested with python3.

Author: Davies Liu <davies@databricks.com>
Author: twneale <twneale@gmail.com>
Author: Josh Rosen <joshrosen@databricks.com>

Closes #5173 from davies/python3 and squashes the following commits:

d7d6323 [Davies Liu] fix tests
6c52a98 [Davies Liu] fix mllib test
99e334f [Davies Liu] update timeout
b716610 [Davies Liu] Merge branch 'master' of github.com:apache/spark into python3
cafd5ec [Davies Liu] adddress comments from @mengxr
bf225d7 [Davies Liu] Merge branch 'master' of github.com:apache/spark into python3
179fc8d [Davies Liu] tuning flaky tests
8c8b957 [Davies Liu] fix ResourceWarning in Python 3
5c57c95 [Davies Liu] Merge branch 'master' of github.com:apache/spark into python3
4006829 [Davies Liu] fix test
2fc0066 [Davies Liu] add python3 path
71535e9 [Davies Liu] fix xrange and divide
5a55ab4 [Davies Liu] Merge branch 'master' of github.com:apache/spark into python3
125f12c [Davies Liu] Merge branch 'master' of github.com:apache/spark into python3
ed498c8 [Davies Liu] fix compatibility with python 3
820e649 [Davies Liu] Merge branch 'master' of github.com:apache/spark into python3
e8ce8c9 [Davies Liu] Merge branch 'master' of github.com:apache/spark into python3
ad7c374 [Davies Liu] fix mllib test and warning
ef1fc2f [Davies Liu] fix tests
4eee14a [Davies Liu] Merge branch 'master' of github.com:apache/spark into python3
20112ff [Davies Liu] Merge branch 'master' of github.com:apache/spark into python3
59bb492 [Davies Liu] fix tests
1da268c [Davies Liu] Merge branch 'master' of github.com:apache/spark into python3
ca0fdd3 [Davies Liu] fix code style
9563a15 [Davies Liu] add imap back for python 2
0b1ec04 [Davies Liu] make python examples work with Python 3
d2fd566 [Davies Liu] Merge branch 'master' of github.com:apache/spark into python3
a716d34 [Davies Liu] test with python 3.4
f1700e8 [Davies Liu] fix test in python3
671b1db [Davies Liu] fix test in python3
692ff47 [Davies Liu] fix flaky test
7b9699f [Davies Liu] invalidate import cache for Python 3.3+
9c58497 [Davies Liu] fix kill worker
309bfbf [Davies Liu] keep compatibility
5707476 [Davies Liu] cleanup, fix hash of string in 3.3+
8662d5b [Davies Liu] Merge branch 'master' of github.com:apache/spark into python3
f53e1f0 [Davies Liu] fix tests
70b6b73 [Davies Liu] compile ec2/spark_ec2.py in python 3
a39167e [Davies Liu] support customize class in __main__
814c77b [Davies Liu] run unittests with python 3
7f4476e [Davies Liu] mllib tests passed
d737924 [Davies Liu] pass ml tests
375ea17 [Davies Liu] SQL tests pass
6cc42a9 [Davies Liu] rename
431a8de [Davies Liu] streaming tests pass
78901a7 [Davies Liu] fix hash of serializer in Python 3
24b2f2e [Davies Liu] pass all RDD tests
35f48fe [Davies Liu] run future again
1eebac2 [Davies Liu] fix conflict in ec2/spark_ec2.py
6e3c21d [Davies Liu] make cloudpickle work with Python3
2fb2db3 [Josh Rosen] Guard more changes behind sys.version; still doesn't run
1aa5e8f [twneale] Turned out `pickle.DictionaryType is dict` == True, so swapped it out
7354371 [twneale] buffer --> memoryview  I'm not super sure if this a valid change, but the 2.7 docs recommend using memoryview over buffer where possible, so hoping it'll work.
b69ccdf [twneale] Uses the pure python pickle._Pickler instead of c-extension _pickle.Pickler. It appears pyspark 2.7 uses the pure python pickler as well, so this shouldn't degrade pickling performance (?).
f40d925 [twneale] xrange --> range
e104215 [twneale] Replaces 2.7 types.InstsanceType with 3.4 `object`....could be horribly wrong depending on how types.InstanceType is used elsewhere in the package--see http://bugs.python.org/issue8206
79de9d0 [twneale] Replaces python2.7 `file` with 3.4 _io.TextIOWrapper
2adb42d [Josh Rosen] Fix up some import differences between Python 2 and 3
854be27 [Josh Rosen] Run `futurize` on Python code:
7c5b4ce [Josh Rosen] Remove Python 3 check in shell.py.

1 files changed, 14 insertions, 22 deletions

diff --git a/python/pyspark/daemon.py b/python/pyspark/daemon.py
index 93885985fe..7f06d4288c 100644
--- a/python/pyspark/daemon.py
+++ b/python/pyspark/daemon.py
@@ -24,9 +24,10 @@ import sys
 import traceback
 import time
 import gc
-from errno import EINTR, ECHILD, EAGAIN
+from errno import EINTR, EAGAIN
 from socket import AF_INET, SOCK_STREAM, SOMAXCONN
 from signal import SIGHUP, SIGTERM, SIGCHLD, SIG_DFL, SIG_IGN, SIGINT
+
 from pyspark.worker import main as worker_main
 from pyspark.serializers import read_int, write_int
 
@@ -53,8 +54,8 @@ def worker(sock):
     # 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)
+    infile = os.fdopen(os.dup(sock.fileno()), "rb", 65536)
+    outfile = os.fdopen(os.dup(sock.fileno()), "wb", 65536)
     exit_code = 0
     try:
         worker_main(infile, outfile)
@@ -68,17 +69,6 @@ def worker(sock):
     return exit_code
 
 
-# Cleanup zombie children
-def cleanup_dead_children():
-    try:
-        while True:
-            pid, _ = os.waitpid(0, os.WNOHANG)
-            if not pid:
-                break
-    except:
-        pass
-
-
 def manager():
     # Create a new process group to corral our children
     os.setpgid(0, 0)
@@ -88,8 +78,12 @@ def manager():
     listen_sock.bind(('127.0.0.1', 0))
     listen_sock.listen(max(1024, SOMAXCONN))
     listen_host, listen_port = listen_sock.getsockname()
-    write_int(listen_port, sys.stdout)
-    sys.stdout.flush()
+
+    # re-open stdin/stdout in 'wb' mode
+    stdin_bin = os.fdopen(sys.stdin.fileno(), 'rb', 4)
+    stdout_bin = os.fdopen(sys.stdout.fileno(), 'wb', 4)
+    write_int(listen_port, stdout_bin)
+    stdout_bin.flush()
 
     def shutdown(code):
         signal.signal(SIGTERM, SIG_DFL)
@@ -101,6 +95,7 @@ def manager():
         shutdown(1)
     signal.signal(SIGTERM, handle_sigterm)  # Gracefully exit on SIGTERM
     signal.signal(SIGHUP, SIG_IGN)  # Don't die on SIGHUP
+    signal.signal(SIGCHLD, SIG_IGN)
 
     reuse = os.environ.get("SPARK_REUSE_WORKER")
 
@@ -115,12 +110,9 @@ def manager():
                 else:
                     raise
 
-            # cleanup in signal handler will cause deadlock
-            cleanup_dead_children()
-
             if 0 in ready_fds:
                 try:
-                    worker_pid = read_int(sys.stdin)
+                    worker_pid = read_int(stdin_bin)
                 except EOFError:
                     # Spark told us to exit by closing stdin
                     shutdown(0)
@@ -145,7 +137,7 @@ def manager():
                         time.sleep(1)
                         pid = os.fork()  # error here will shutdown daemon
                     else:
-                        outfile = sock.makefile('w')
+                        outfile = sock.makefile(mode='wb')
                         write_int(e.errno, outfile)  # Signal that the fork failed
                         outfile.flush()
                         outfile.close()
@@ -157,7 +149,7 @@ def manager():
                     listen_sock.close()
                     try:
                         # Acknowledge that the fork was successful
-                        outfile = sock.makefile("w")
+                        outfile = sock.makefile(mode="wb")
                         write_int(os.getpid(), outfile)
                         outfile.flush()
                         outfile.close()