[Zope-dev] [Warning] Zope/ZEO clients: subprocesses can lead tonon-deterministic message loss:MAYBE NOT

Tim Peters tim.peters at gmail.com
Sun Jun 27 17:57:53 EDT 2004


[sathya]
> thanks for the clarification below and also the pointers to the posix
> behaviour of fork. The Warning about Zope/ZEO clients in the subject
> line certainly caused some alarm bells to go off.
>
> I am assuming now that dieters description below of using forks does not
> gel with the ZOPE/ZEO process model i.e  there are no forks being called
> within the code to cause the asyncore thread to be cloned

I'm still not clear on either exactly what Dieter did, or on what kind
of system.  In any case, he wasn't talking about forks in Zope/ZEO
directly, but about forks in *application* code.  The presence (or
absence) of those depends on what applications do, not on what
Zope/ZEO do.

> (  even if one were using a non posix compliant thread lib like native solaris it
> would still be a non issue ).

I don't think we know enough yet to say.  I've never used native
Solaris threads, and they're so different from POSIX threads in this
respect that I'm not going to guess about how ugly life can be with
them.  I'm sure there's no problem here with native Windows threads. 
I don't *see* a way for there to be a problem under POSIX thread
semantics, but then I'm still guessing too much about what Dieter
actually did.

If I were you, I'd ignore this thread until it reaches a conclusion --
if there were widespread problems here, we would have heard about them
before in the multiple years Zope and ZEO have been in production (and
even under Solaris, I believe most people chose to use Sun's POSIX
threads implementation, not the native Solaris threads).


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