Commit 1bd27dd7 authored by Tim Peters's avatar Tim Peters

Worm around suspected Windows socket bug in Windows trigger code.

See the thread starting at
 http://mail.zope.org/pipermail/zope/2005-July/160433.html
for gory details.

Note that Zope trunk and 2.8 also have a third copy of this
code, in

    lib/python/zope/server/trigger.py

That's "a Zope3 problem".
parent ce99904b
......@@ -26,6 +26,15 @@ Zope Changes
Bugs Fixed
- As developed in a long thread starting at
http://mail.zope.org/pipermail/zope/2005-July/160433.html
there appears to be a race bug in the Microsoft Windows socket
implementation, rarely visible in ZEO and/or in
ZServer/medusa/thread/select_trigger.py when multiple processes try
to create an "asyncore trigger" simultaneously, most often (in
stress tests) manifesting as a hung process. Windows-specific
trigger code in both changed to work around this bug when it occurs.
- Collector #1807: fixed memory leak in cAccessControl.guarded_getattr()
......
......@@ -9,6 +9,7 @@ import os
import socket
import string
import thread
import errno
if os.name == 'posix':
......@@ -95,59 +96,82 @@ else:
class BindError(Exception):
pass
class trigger (asyncore.dispatcher):
address = ('127.9.9.9', 19999)
class trigger(asyncore.dispatcher):
def __init__ (self):
a = socket.socket (socket.AF_INET, socket.SOCK_STREAM)
w = socket.socket (socket.AF_INET, socket.SOCK_STREAM)
# set TCP_NODELAY to true to avoid buffering
w.setsockopt(socket.IPPROTO_TCP, 1, 1)
# tricky: get a pair of connected sockets
host='127.0.0.1'
port=19999
# The __init__ code is taken from ZODB 3.4.1's
# ZEO/zrpc/trigger.py, to worm around problems in the original
# Windows __init__ code.
# Get a pair of connected sockets. The trigger is the 'w'
# end of the pair, which is connected to 'r'. 'r' is put
# in the asyncore socket map. "pulling the trigger" then
# means writing something on w, which will wake up r.
w = socket.socket()
# Disable buffering -- pulling the trigger sends 1 byte,
# and we want that sent immediately, to wake up asyncore's
# select() ASAP.
w.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
count = 0
while 1:
count += 1
# Bind to a local port; for efficiency, let the OS pick
# a free port for us.
# Unfortunately, stress tests showed that we may not
# be able to connect to that port ("Address already in
# use") despite that the OS picked it. This appears
# to be a race bug in the Windows socket implementation.
# So we loop until a connect() succeeds (almost always
# on the first try). See the long thread at
# http://mail.zope.org/pipermail/zope/2005-July/160433.html
# for hideous details.
a = socket.socket()
a.bind(("127.0.0.1", 0))
connect_address = a.getsockname() # assigned (host, port) pair
a.listen(1)
try:
self.address=(host, port)
a.bind(self.address)
break
except:
if port <= 19950:
raise BindError, 'Cannot bind trigger!'
port=port - 1
w.connect(connect_address)
break # success
except socket.error, detail:
if detail[0] != errno.WSAEADDRINUSE:
# "Address already in use" is the only error
# I've seen on two WinXP Pro SP2 boxes, under
# Pythons 2.3.5 and 2.4.1.
raise
# (10048, 'Address already in use')
# assert count <= 2 # never triggered in Tim's tests
if count >= 10: # I've never seen it go above 2
a.close()
w.close()
raise BindError("Cannot bind trigger!")
# Close `a` and try again. Note: I originally put a short
# sleep() here, but it didn't appear to help or hurt.
a.close()
a.listen (1)
w.setblocking (0)
try:
w.connect (self.address)
except:
pass
r, addr = a.accept()
r, addr = a.accept() # r becomes asyncore's (self.)socket
a.close()
w.setblocking (1)
self.trigger = w
asyncore.dispatcher.__init__ (self, r)
self.lock = thread.allocate_lock()
self.thunks = []
self._trigger_connected = 0
def __repr__ (self):
def __repr__(self):
return '<select-trigger (loopback) at %x>' % id(self)
def readable (self):
def readable(self):
return 1
def writable (self):
def writable(self):
return 0
def handle_connect (self):
def handle_connect(self):
pass
def pull_trigger (self, thunk=None):
def pull_trigger(self, thunk=None):
if thunk:
try:
self.lock.acquire()
......@@ -156,8 +180,8 @@ else:
self.lock.release()
self.trigger.send ('x')
def handle_read (self):
self.recv (8192)
def handle_read(self):
self.recv(8192)
try:
self.lock.acquire()
for thunk in self.thunks:
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment