Use tornado wsgi server as werkzeug crashes on Internet Explorer

libs/tornado/process.py

@@ -0,0 +1,149 @@
+#!/usr/bin/env python
+#
+# Copyright 2011 Facebook
+#
+# Licensed 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.
+
+"""Utilities for working with multiple processes."""
+
+import errno
+import logging
+import os
+import sys
+import time
+
+from binascii import hexlify
+
+from tornado import ioloop
+
+try:
+    import multiprocessing # Python 2.6+
+except ImportError:
+    multiprocessing = None
+
+def cpu_count():
+    """Returns the number of processors on this machine."""
+    if multiprocessing is not None:
+        try:
+            return multiprocessing.cpu_count()
+        except NotImplementedError:
+            pass
+    try:
+        return os.sysconf("SC_NPROCESSORS_CONF")
+    except ValueError:
+        pass
+    logging.error("Could not detect number of processors; assuming 1")
+    return 1
+
+def _reseed_random():
+    if 'random' not in sys.modules:
+        return
+    import random
+    # If os.urandom is available, this method does the same thing as
+    # random.seed (at least as of python 2.6).  If os.urandom is not
+    # available, we mix in the pid in addition to a timestamp.
+    try:
+        seed = long(hexlify(os.urandom(16)), 16)
+    except NotImplementedError:
+        seed = int(time.time() * 1000) ^ os.getpid()
+    random.seed(seed)
+
+
+_task_id = None
+
+def fork_processes(num_processes, max_restarts=100):
+    """Starts multiple worker processes.
+
+    If ``num_processes`` is None or <= 0, we detect the number of cores
+    available on this machine and fork that number of child
+    processes. If ``num_processes`` is given and > 0, we fork that
+    specific number of sub-processes.
+
+    Since we use processes and not threads, there is no shared memory
+    between any server code.
+
+    Note that multiple processes are not compatible with the autoreload
+    module (or the debug=True option to `tornado.web.Application`).
+    When using multiple processes, no IOLoops can be created or
+    referenced until after the call to ``fork_processes``.
+
+    In each child process, ``fork_processes`` returns its *task id*, a
+    number between 0 and ``num_processes``.  Processes that exit
+    abnormally (due to a signal or non-zero exit status) are restarted
+    with the same id (up to ``max_restarts`` times).  In the parent
+    process, ``fork_processes`` returns None if all child processes
+    have exited normally, but will otherwise only exit by throwing an
+    exception.
+    """
+    global _task_id
+    assert _task_id is None
+    if num_processes is None or num_processes <= 0:
+        num_processes = cpu_count()
+    if ioloop.IOLoop.initialized():
+        raise RuntimeError("Cannot run in multiple processes: IOLoop instance "
+                           "has already been initialized. You cannot call "
+                           "IOLoop.instance() before calling start_processes()")
+    logging.info("Starting %d processes", num_processes)
+    children = {}
+    def start_child(i):
+        pid = os.fork()
+        if pid == 0:
+            # child process
+            _reseed_random()
+            global _task_id
+            _task_id = i
+            return i
+        else:
+            children[pid] = i
+            return None
+    for i in range(num_processes):
+        id = start_child(i)
+        if id is not None: return id
+    num_restarts = 0
+    while children:
+        try:
+            pid, status = os.wait()
+        except OSError, e:
+            if e.errno == errno.EINTR:
+                continue
+            raise
+        if pid not in children:
+            continue
+        id = children.pop(pid)
+        if os.WIFSIGNALED(status):
+            logging.warning("child %d (pid %d) killed by signal %d, restarting",
+                            id, pid, os.WTERMSIG(status))
+        elif os.WEXITSTATUS(status) != 0:
+            logging.warning("child %d (pid %d) exited with status %d, restarting",
+                            id, pid, os.WEXITSTATUS(status))
+        else:
+            logging.info("child %d (pid %d) exited normally", id, pid)
+            continue
+        num_restarts += 1
+        if num_restarts > max_restarts:
+            raise RuntimeError("Too many child restarts, giving up")
+        new_id = start_child(id)
+        if new_id is not None: return new_id
+    # All child processes exited cleanly, so exit the master process
+    # instead of just returning to right after the call to
+    # fork_processes (which will probably just start up another IOLoop
+    # unless the caller checks the return value).
+    sys.exit(0)
+
+def task_id():
+    """Returns the current task id, if any.
+
+    Returns None if this process was not created by `fork_processes`.
+    """
+    global _task_id
+    return _task_id