[Zope-DB] Re: SQL Relay

Chris Withers chrisw at nipltd.com
Thu Oct 30 13:42:27 EST 2003

Hi Kent,

I'm moving this onto the zope-db list since it's revelent there...

Kent Hoxsey wrote:

>>>The place I've run into troubles is with scalability. I have been unable to find a way
>>>to configure Zope so that it can run more than 2 ZSQL methods at one time. 
>>What do you mean by this?

> The problem is that some of the SQL runs for a long time (1-2 minutes). Obviously,
> the load is on the database server, not the Zope server, so you would think the Zope
> server would be able to handle an amazing number of these requests.

Well, each Zope thread has to wait for the DB that it's accessing. Zope has 4 
threads, by default, IIRC.

> that turns out not to be the case. Once Zope starts running the second long ZSQL,
> it effectively stops accepting requests until one of the two ZSQLs completes.

Hmm, that sounds like something somewhere is blocking... What database adapters 
does this happen with? What adapters does it not happen with?

> I figured it was a threading issue, so I raised the number of threads for Zope, then
> the number of threads for the ZODB, all to no effect. I changed database connectors,
> with no effect. At this point, I assume the issue has to do with Zope's thread scheduling,
> but have not had a chance to dig that far into the problem.

Nope, it ain't that. Might well be your back end database...

> the same hardware, and I've validated that it's not the Oracle connection stuff, even
> using python. We're both pretty sure it's Zope, but just don't know where the problem
> resides.

What databases does it affect? Only Oracle?



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