Tornado 3.2.1

libs/tornado/process.py

@@ -21,7 +21,6 @@ the server into multiple processes and managing subprocesses.
 from __future__ import absolute_import, division, print_function, with_statement
 
 import errno
-import multiprocessing
 import os
 import signal
 import subprocess
@@ -35,6 +34,13 @@ from tornado.iostream import PipeIOStream
 from tornado.log import gen_log
 from tornado.platform.auto import set_close_exec
 from tornado import stack_context
+from tornado.util import errno_from_exception
+
+try:
+    import multiprocessing
+except ImportError:
+    # Multiprocessing is not availble on Google App Engine.
+    multiprocessing = None
 
 try:
     long  # py2
@@ -44,6 +50,8 @@ except NameError:
 
 def cpu_count():
     """Returns the number of processors on this machine."""
+    if multiprocessing is None:
+        return 1
     try:
         return multiprocessing.cpu_count()
     except NotImplementedError:
@@ -136,7 +144,7 @@ def fork_processes(num_processes, max_restarts=100):
         try:
             pid, status = os.wait()
         except OSError as e:
-            if e.errno == errno.EINTR:
+            if errno_from_exception(e) == errno.EINTR:
                 continue
             raise
         if pid not in children:
@@ -283,7 +291,7 @@ class Subprocess(object):
         try:
             ret_pid, status = os.waitpid(pid, os.WNOHANG)
         except OSError as e:
-            if e.args[0] == errno.ECHILD:
+            if errno_from_exception(e) == errno.ECHILD:
                 return
         if ret_pid == 0:
             return