[Zope-dev] Zope 2.X BIG Session problems - blocker - our site dies - need help of experience Zope developer, please

[Chris McDonough]

On Sat, 2004-02-28 at 04:07, alex at halogen-dg.com wrote:
> Hi
> 
> On Tue, 24 Feb 2004, Chris McDonough wrote:
> 
> > Yes, it's still broke.  No, there is no fix.  Sorry.
> 
> Thanks Cris. Thats very bad.

Yes it is.

> It is very bad from end-user perspective that
> such critical bug has been found more then year ago, and nobody at Zope
> has fixed their code during a year time.

Yes it is.  Although this is not really Zope Corporation's fault, this
is my fault.  I should have tested the sessioning machinery better under
high load and found that it was broken before putting it in (way back in
2.5).  Sessions should just not be in there now, but it's not reasonable
to take them out, as they fall over under high load.  However, they work
just fine under light load, so no one but the people who have high load
see the issue.

So I'm hoping that someone will take it upon themselves to fix the
problem or provide the resources necessary to fix them.  I just haven't
been able to do so yet.
 
> I am trying to read all the things you have discussed in March 2003, but 
> it is very difficult to understand how to fix that. Also, I am in doubt I 
> will be able to do that, because if Zope-experienced developers can not 
> fix it, my chances are low. 
> 
> I just have no choice - we already developed a product for Zope, so I have 
> to support it. Even if it requires hacking of application server itself.
> 
> I see that fix:
> 
>         #db.klass = LowConflictConnection
> 
> but it does not work for us. At least we keep seeing the session
> errors with any Zope version - we tries Zope 2.6.4, Zope 2.7.0 with 
> same results.

Right.  Doesn't help, apparently.

> 
> So, as far I you see, as soon as Zope starts using sessions, and when 
> there are many customers, the site is dead for some users. 
> 
> Once 'get' error occurs to a specific Session, the customer is blocked
> and is not able to see any page on the site: all pages produce this get 
> error. 

Well, you could work around this in your app code, but obviously it
should not be necessary.

> That is very critital and 'blocker' bug for Zope. I do not understand how
> people could use Zope on a sites with high load..

They don't use sessions under high load.

> 
> The only thing which works is asking customer  to delete all Cookies, so 
> session ends, and new one starts. This is very ugly fix, you understand...
> 
> I am not Zope hacker itself, we are just building sites, we are not 
> developers of Server solutions in most of time, so it takes time to study 
> the Zope code to be able to fix that...
> 
> I will try to work on this more and more, but ... Its just very difficult. 

Right, otherwise it would be fixed by now.

> 
> Anybody, experienced with Zope developmnet could help me? I am sure, this 
> problem could happend to anyone running a big Zope site. Is anybody
> interested in helping to resolve this blocker Zope+Sessions issue?
> 
> As soon as you start getting more hits to any Zope based site, the more 
> customers will not see it because of Session problem. 
> 
> I do not know how many customers of our site getting this, but we do 
> get it everyday several times a day / person. So, in my understanding Zope 
> Session is completely broken. It works fine for a several customers/ hour, 
> but when things come to 1000 visits/ hour, it just stops functionaning 
> properly. 
> 
> I will be trying to study Zope code.... That is what Open Source for, and
> I am a big fun of that. But of course, it does not help much if you are 
> not experienced with product itself. It takes time to learn it.
> 
> But I will try. If anybody interested in help, it would be great. at the
> current moment I am trying to stable reproduce the prob, but it 
> seems it only happends on a site with high load.

I can't promise anything, but I will try to help by answering pointed
questions where possible.

- C