[Zope] urgent stability problem on production site

[Matthew T. Kromer]

Frank Tegtmeyer wrote:

>"Matthew T. Kromer" <matt@zope.com> writes:
>
>>Frank, try starting Zope up single-threaded ( -t 1 ) and see if that
>>helps; I'm nervous about a potential problem with the MySQLDA C
>>libraries having thread-local data and switching threads leading to
>>instability.
>>
>
>I have set this - now Zope doesn't want to die :) I will have to wait
>for the next error to see the effect.
>
>>We've had one customer who 'made the problems go away'
>>when they ran single-threaded Zope.
>>
>
>Interesting - aren't the MySQL connections bound to a thread? YOu mean
>there may be a bug at a lower level than mysql-python?
>
>Regards, Frank
>

Well, I'm worried about the MySQL libraries.  You can build them either 
in threaded or nonthreaded mode; and the default setup of ZMySQLDA was 
to use the nonthreaded libraries.  So that's a problem right there.

Secondly, Andy Dustman thought that certain library objects were 
thread-bound -- so you couldn't allocate a connection object on one 
thread and then invoke it from another.  Zope would try to do that as 
part of the DA connection pooling.  I have a patch for ZMySQLDA which 
tries to close and reopen the MySQL connection when the DA connection 
object switches threads, but I haven't ever heard from someone "this 
fixes it!"

I personally haven't got a reproducable test case in house to try to 
diagnose the MySQL problems.  When I do simple queries etc by banging on 
the Zope SQL Methods with "ab" I don't have MySQL fail.