[Zope] Zope 2.8 and conflict errors

Maciej Wisniowski maciej.wisniowski at coig.katowice.pl
Fri Aug 5 03:23:52 EDT 2005


 > That looks like a write conflict. MVCC helps to lower/eliminate the  
rate of read conflicts.
 > One option to reduce the rate of this write conflict is to tune the  
session machinery to suit.
 > For example use session-resolution-seconds  of say 300 seconds.
Thanks!
I've changed session-resolution-seconds and did some tests again.
With DCOracle 2 there are still some errors (30 conflicts visible for users
for 3000 requests), but with SQLRelay there are no errors at all! :)
I didn't checked all 30 errors but I think these are all conflicts 
errors with
Products.DCOracle2.DA.Procedure object like this one:

<P>An error was encountered while publishing this resource.
</P>
<P><STRONG>ZODB.POSException.ConflictError</STRONG></P>
  Sorry, a site error occurred.<p><p>Traceback (innermost last):
<ul>
<li>  Module ZPublisher.Publish, line 187, in publish_module_standard</li>
<li>  Module ZPublisher.Publish, line 161, in publish</li>
<li>  Module ZPublisher.Publish, line 161, in publish</li>
<li>  Module ZPublisher.Publish, line 161, in publish</li>
<li>  Module ZPublisher.Publish, line 151, in publish</li>
<li>  Module Zope2.App.startup, line 158, in zpublisher_exception_hook</li>
<li>  Module ZPublisher.Publish, line 119, in publish</li>
<li>  Module Zope2.App.startup, line 215, in commit</li>
<li>  Module transaction._manager, line 84, in commit</li>
<li>  Module transaction._transaction, line 381, in commit</li>
<li>  Module transaction._transaction, line 379, in commit</li>
<li>  Module transaction._transaction, line 427, in _commitResources</li>
<li>  Module ZODB.Connection, line 637, in tpc_vote</li>
<li>  Module ZEO.ClientStorage, line 893, in tpc_vote</li>
<li>  Module ZEO.ClientStorage, line 877, in _check_serials</li>
</ul>ConflictError: database conflict error (oid 0x0299de, class
        Products.DCOracle2.DA.Procedure, serial this txn started
with 0x035f181b76214155 2005-08-04 08:59:27.686696, serial
currently committed 0x035f181b79752811 2005-08-04 08:59:28.466635)

Any ideas what can be done to remove this problem, except the obvious
solution - that is moving to SQLRelay ;) I tried _p_resolveConflict 
function
but without effect - it's used to resolve write conflict and I suppose 
these
errors like the one above are read conflicts.

-- 
Maciej Wisniowki


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