[Zope] Re: zope unresponsive

[Tres Seaver]

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Paul Williams wrote:
> Ok, here is what we have.  I did a netstat on both machines, client and 
> server.  The client sees and established connection and the server does 
> not.  In the server log there is a disconnect.  As far as hardware 
> between them, there is a switch (dell powerconnect 6024).  Web Server 
> Directors might get hold of it but there are no hops on traceroute. 
> Traceroute only shows the client machine and the server machine.
> 
> So the client is just continuously polling the connection but getting 
> nothing back.

That sounds like some weird kernel / networking problem to me:  I don't
see how Zope could be able to keep calling 'select' on a socket after
the other side has closed it.

Is there any possibility that some kind of failover / IP takeover has
happened, such that the storage server now running is not the same host
/ instance as the one to shich the clients originally connected?  Are
you using LVS + heartbeat, or some kind of hardware load balancer to
manage such redundancy?

> What we are thinking about doing is changing the code in 
> zrpc/connection.py to close the connection in wait (line 638 zope 
> version 2.9.5) if the wait time gets too large or the poll has happened 
> too many times.
> 
> We are great at plone development, but have very little backend zope 
> development.  Would someone please advise me as to whether this is going 
> to cause more problems?

According to the log message you posted earlier in the thread, your
appservers are spewing thousands of log messages from the connection's
'pending' method, although your deadlock debugger output shows the one
thread blocked on 'select' inside of the connection's 'wait' method.
There should be lots of log messages at TRACE level for the wait call,
including a doubling / backoff of the delay value from 1 mx to 1 sec.
Do you see those log messages, as well?


Tres.
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Tres Seaver          +1 540-429-0999          tseaver at palladion.com
Palladion Software   "Excellence by Design"    http://palladion.com
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