Commit fbcef1c2 authored by Tim Peters's avatar Tim Peters

Merge rev 37631 from 3.4 branch.

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.
parent 8c081bef
......@@ -88,6 +88,16 @@ Tools
- (3.5a5) Collector #1846: If an uncommitted transaction was found,
fsrecover.py fell into an infinite loop.
Windows
-------
- (3.5a6) 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 when multiple processes try to
create an "asyncore trigger" simultaneously. Windows-specific code in
``ZEO/zrpc/trigger.py`` changed to work around this bug when it occurs.
ThreadedAsync.LoopCallback
--------------------------
......@@ -156,6 +166,7 @@ Release date: DD-MMM-2005
Following are dates of internal releases (to support ongoing Zope 2
development) since ZODB 3.4's last public release:
- 3.4.1b2 DD-MMM-2005
- 3.4.1b1 26-Jul-2005
- 3.4.1a6 19-Jul-2005
- 3.4.1a5 12-Jul-2005
......@@ -257,6 +268,17 @@ ThreadedAsync.LoopCallback
example, debugging prints added to Python's ``asyncore.loop`` won't be lost
anymore).
Windows
-------
- (3.4.1b2) 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 when multiple processes try to
create an "asyncore trigger" simultaneously. Windows-specific code in
``ZEO/zrpc/trigger.py`` changed to work around this bug when it occurs.
Tools
-----
......
##############################################################################
#
# Copyright (c) 2001, 2002 Zope Corporation and Contributors.
# Copyright (c) 2001-2005 Zope Corporation and Contributors.
# All Rights Reserved.
#
# This software is subject to the provisions of the Zope Public License,
......@@ -156,27 +156,61 @@ else:
def __init__(self):
_triggerbase.__init__(self)
# 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.
a = socket.socket() # temporary, to set up the connection
w = socket.socket()
self.trigger = w
# set TCP_NODELAY to true to avoid buffering
w.setsockopt(socket.IPPROTO_TCP, 1, 1)
# Specifying port 0 tells Windows to pick a port for us.
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:
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()
r, addr = a.accept() # r becomes asyncore's (self.)socket
a.close()
self.trigger = w
asyncore.dispatcher.__init__(self, r)
def _close(self):
# self.socket is r, self.trigger is w from __init__
# self.socket is r, and self.trigger is w, from __init__
self.socket.close()
self.trigger.close()
......
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