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[Warning] Zope/ZEO clients: subprocesses can lead to non-deterministic message loss
by Dieter Maurer 29 Jun '04

29 Jun '04

ATTENTION: Crosspost -- Reply-To set to 'zope-dev(a)zope.org' Today, I hit a nasty error. The error affects applications under Unix (and maybe Windows) which * use an "asyncore" mainloop thread (and maybe other asyncore applications) Zope and many ZEO clients belong to this class and * create subprocesses (via "fork" and "system", "popen" or friends if they use "fork" internally (they do under Unix but I think not under Windows)). The error can cause non-deterministic loss of messages (HTTP requests, ZEO server responses, ...) destined for the parent process. It also can cause the same output to be send several times over sockets. The error is explained as follows: "asyncore" maintains a map from file descriptors to handlers. The "asyncore" main loop waits for any file descriptor to become "active" and then calls the corresponding handler. When a process forks the complete state, including file descriptors, threads and memory state is copied and the new process executes in this copied state. We now have 2 "asyncore" threads waiting for the same events. File descriptors are shared between parent and child. When the child reads from a file descriptor from its parent, it steals the corresponding message: the message will not reach the parent. While file descriptors are shared, memory state is separate. Therefore, pending writes can be performed by both parent and child -- leading to duplicate writes to the same file descriptor. A workaround it to deactivate "asyncore" before forking (or "system", "popen", ...) and reactivate it afterwards: as exemplified in the following code: from asyncore import socket_map saved_socket_map = socket_map.copy() socket_map.clear() # deactivate "asyncore" pid = None try: pid = fork() if (pid == 0): # child # ... finally: if pid != 0: socket_map.update(saved_socket_map) # reactivate "asyncore" -- Dieter

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by Astor Industrial Corporation 29 Jun '04

29 Jun '04

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by caroool2003 29 Jun '04

29 Jun '04

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by postmaster＠mail.dfa.gov.ph 29 Jun '04

29 Jun '04

V I R U S A L E R T Our viruschecker found a VIRUS in your email to the following recipient(s): -> cairope(a)dfa.gov.ph Please check your system for viruses, or ask your system administrator to do so. For further information about this viruschecker see: http://amavis.org/ AMaViS - A Mail Virus Scanner, licensed GPL For your reference, here are the headers from your email: ------------------------- BEGIN HEADERS ----------------------------- Received: from dfa.gov.ph (host93-191.pool82105.interbusiness.it [82.105.191.93]) by mail.dfa.gov.ph (Postfix) with ESMTP id CACB37D314 for <cairope(a)dfa.gov.ph>; Tue, 29 Jun 2004 15:27:51 +0800 (PHT) From: zope-dev(a)zope.org To: cairope(a)dfa.gov.ph Subject: Mail Delivery (failure cairope(a)dfa.gov.ph) Date: Tue, 29 Jun 2004 09:28:24 +0200 MIME-Version: 1.0 Content-Type: multipart/related; type="multipart/alternative"; boundary="----=_NextPart_000_001B_01C0CA80.6B015D10" X-Priority: 3 X-MSMail-Priority: Normal Message-Id: <20040629072751.CACB37D314(a)mail.dfa.gov.ph> -------------------------- END HEADERS ------------------------------

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29 Jun '04

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28 Jun '04

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by Luisa Womack 28 Jun '04

28 Jun '04

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28 Jun '04

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June Bug Day Roundup
by Chris Withers 28 Jun '04

28 Jun '04

Hi All, A quieter Bug Day than before, hopefully due to my late announcement and the fun and games we've been having with the lists of late. Nevertheless, here's the bugs that were processed from the Zope collector: Fixed: #1384 - len(LazyCat) problems #1386 - DateTime cannot parse some ISO 8601 dates Wontfix: #1278 - custom_zodb.py usage in Zope 2.7 #1377 - now broken ObjectManager "delete protocol": _on_delete_object Rejected: #566 - ZCatalog sort problems when some objects missing the sort property #988 - manage_delObjects called with tuples #1019 - problems with bin/mkzopeinstance -d var #1348 - dtml namespaces issues #1385 - Zope3 PageTemplate interface changes break traversal Thanks for all those who pitched in, particularly Andreas Jung and Martijn Pieters who were top bug handlers... Next one is the end of July... cheers, Chris -- Simplistix - Content Management, Zope & Python Consulting - http://www.simplistix.co.uk

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Re: Zope-Dev Digest, Vol 11, Issue 33
by Stéphane JULIEN 28 Jun '04

28 Jun '04

Attention! It seems you have got a virus on your machine! Please make sure you have the latest update of your virus scanner and check all your files right away! Take care, zope-dev-request(a)zope.org

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