Laurence, There are three things. First, though I am writing to the same object, I am only doing a write every 10 seconds. That is an eternity in cpu time. I would not expect many conflicts to occur in eternity. Secondly, the conflict happens EVERY time from whichever program was started first. There is no randomness to it. Third, I start the second program a few seconds after the first, so there should be an offset of when each program writes to the database.
I have looked at the chatter page that you referred me to, but It is the way that I do things to start small. And small in this case means to be able to write to a ZEO database from two programs without a conflict. What you said doesn't make sense to me. I would appreciate it if you could expound some to help me understand why. thanks again, tom Laurence Rowe wrote: > > With that setup, you would expect a lot of conflicts, you are > continually writing to the same object from more than one client. You > will see many fewer conflicts if the different clients wrote to > different objects or updated an object with conflict resolution (for > instance inserting into a BTree). > > You may find the example application at > http://docs.zope.org/zodb/zodbguide/zeo.html#sample-application-chatter-py > helpful. I've updated the conflict handling and links, but it will > take a few hours for the update to be published to the website. In the > meantime it may be downloaded from svn: > http://svn.zope.org/zodbdocs/trunk/zodbguide/chatter.py?view=auto > helpful. > > Laurence > > 2009/11/26 tsmiller <tsmil...@gnixterhouse.com>: >> >> Laurence, >> Thank you for your very quick reply. I did as you suggested and now the >> ConflictError is now handled. And that is a most excellent thing because >> now ConflictError is raised every time. So it still seems to be >> confused. >> I am trying to figure out if I will be able to use ZEO in my application. >> >> Now my program reads: >> >> while True: >> root[ "one" ] = time.asctime() >> while True: >> try: >> print "Try to commit transaction" >> transaction.commit() >> print "root is", root >> except POSException.ConflictError: >> print "we have a conflict" >> transaction.abort() >> time.sleep(.2) >> else: >> break >> >> time.sleep(10) >> >> >> And the output is: >> >> // the program is only running once here >> Try to commit transaction >> root is {'one': 'Thu Nov 26 11:37:53 2009'} >> Try to commit transaction >> root is {'one': 'Thu Nov 26 11:38:03 2009'} >> Try to commit transaction >> root is {'one': 'Thu Nov 26 11:38:13 2009'} >> Try to commit transaction >> root is {'one': 'Thu Nov 26 11:38:23 2009'} >> Try to commit transaction >> root is {'one': 'Thu Nov 26 11:38:33 2009'} >> >> // after I start a second copy, the first copy always has a conflict ( >> the >> second copy does not get this conflict error). >> Try to commit transaction >> we have a conflict >> Try to commit transaction >> root is {'one': 'Thu Nov 26 11:38:35 2009'} >> Try to commit transaction >> we have a conflict >> Try to commit transaction >> root is {'one': 'Thu Nov 26 11:38:46 2009'} >> Try to commit transaction >> we have a conflict >> Try to commit transaction >> root is {'one': 'Thu Nov 26 11:38:56 2009'} >> Try to commit transaction >> we have a conflict >> >> thanks, >> tom >> >> >> >> Laurence Rowe wrote: >>> >>> You must be prepared to abort and retry the whole transaction: >>> >>> while True: >>> while True: >>> try: >>> root[ "one" ] = time.asctime() >>> transaction.commit() >>> except POSException.ConflictError: >>> transaction.abort() >>> time.sleep(.2) >>> else: >>> break >>> >>> time.sleep(10) >>> >>> >>> Laurence >>> >>> 2009/11/26 tsmiller <tsmil...@gnixterhouse.com>: >>>> >>>> ZODB Developers, >>>> >>>> Can you please tell me what I am doing wrong in my first simple attempt >>>> to >>>> make use of ZEO. My ZODB and ZEO are both the same version (3.6.0). >>>> >>>> First, I start my ZEO server and it looks like it starts properly: >>>> >>>> python2.4 /usr/lib/python2.4/site-packages/ZEO/runzeo.py -a >>>> localhost:9100 >>>> -f /home/tom/zeo/test.fs >>>> >>>> ------ >>>> 2009-11-26T00:05:14 INFO ZEO.runzeo (8192) opening storage '1' using >>>> FileStorage >>>> ------ >>>> 2009-11-26T00:05:14 INFO ZEO.StorageServer (8192) StorageServer created >>>> RW >>>> with storages: 1:RW:/home/tom/zeo/test.fs >>>> ------ >>>> 2009-11-26T00:05:14 INFO ZEO.zrpc (8192) listening on ('localhost', >>>> 9100) >>>> >>>> >>>> Second, I start my client, twice. The purpose is to write to the same >>>> test.fs file from both of them. The idea is to loop continuously, >>>> writing >>>> to test.fs from each program. If I only start the program once, it >>>> writes >>>> to test.fs fine. But the first time it tries to commit a transaction >>>> after >>>> starting a second copy of the program, it always gives an error. >>>> >>>> from ZEO import ClientStorage >>>> from ZODB import DB >>>> from ZODB import POSException >>>> import transaction >>>> import time >>>> >>>> addr = 'localhost', 9100 >>>> storage = ClientStorage.ClientStorage( addr ) >>>> db = DB(storage) >>>> conn = db.open() >>>> root = conn.root() >>>> while True: >>>> root[ "one" ] = time.asctime() >>>> while True: >>>> try: >>>> transaction.commit() >>>> except POSException.ConflictError: >>>> time.sleep(.2) >>>> else: >>>> break >>>> >>>> time.sleep(10) >>>> >>>> >>>> The traceback folows. The conflict error is not handled and I don't >>>> know >>>> why. I am sure that I am missing something simple. >>>> >>>> we have a conflict >>>> Traceback (most recent call last): >>>> File "zeotest.py", line 17, in ? >>>> transaction.commit() >>>> File "/usr/lib/python2.4/site-packages/transaction/_manager.py", line >>>> 96, >>>> in commit >>>> return self.get().commit(sub, deprecation_wng=False) >>>> File "/usr/lib/python2.4/site-packages/transaction/_transaction.py", >>>> line >>>> 370, in commit >>>> self._prior_operation_failed() # doesn't return >>>> File "/usr/lib/python2.4/site-packages/transaction/_transaction.py", >>>> line >>>> 250, in _prior_operation_failed >>>> raise TransactionFailedError("An operation previously failed, " >>>> ZODB.POSException.TransactionFailedError: An operation previously >>>> failed, >>>> with traceback: >>>> >>>> File "zeotest.py", line 17, in ? >>>> transaction.commit() >>>> File "/usr/lib/python2.4/site-packages/transaction/_manager.py", line >>>> 96, >>>> in commit >>>> return self.get().commit(sub, deprecation_wng=False) >>>> File "/usr/lib/python2.4/site-packages/transaction/_transaction.py", >>>> line >>>> 380, in commit >>>> self._saveCommitishError() # This raises! >>>> File "/usr/lib/python2.4/site-packages/transaction/_transaction.py", >>>> line >>>> 378, in commit >>>> self._commitResources() >>>> File "/usr/lib/python2.4/site-packages/transaction/_transaction.py", >>>> line >>>> 433, in _commitResources >>>> rm.commit(self) >>>> File "/usr/lib/python2.4/site-packages/ZODB/Connection.py", line 484, >>>> in >>>> commit >>>> self._commit(transaction) >>>> File "/usr/lib/python2.4/site-packages/ZODB/Connection.py", line 518, >>>> in >>>> _commit >>>> raise ConflictError(object=obj) >>>> ConflictError: database conflict error (oid 0x00, class >>>> persistent.mapping.PersistentMapping) >>>> >>>> >>>> thanks, >>>> >>>> tom >>>> >>>> >>>> -- >>>> View this message in context: >>>> http://old.nabble.com/newbie-ZEO-first-try.--ConflictError.-tp26532984p26532984.html >>>> Sent from the Zope - ZODB-Dev mailing list archive at Nabble.com. >>>> >>>> _______________________________________________ >>>> For more information about ZODB, see the ZODB Wiki: >>>> http://www.zope.org/Wikis/ZODB/ >>>> >>>> ZODB-Dev mailing list - zodb-...@zope.org >>>> https://mail.zope.org/mailman/listinfo/zodb-dev >>>> >>> _______________________________________________ >>> For more information about ZODB, see the ZODB Wiki: >>> http://www.zope.org/Wikis/ZODB/ >>> >>> ZODB-Dev mailing list - zodb-...@zope.org >>> https://mail.zope.org/mailman/listinfo/zodb-dev >>> >>> >> >> -- >> View this message in context: >> http://old.nabble.com/newbie-ZEO-first-try.--ConflictError.-tp26532984p26533587.html >> Sent from the Zope - ZODB-Dev mailing list archive at Nabble.com. >> >> _______________________________________________ >> For more information about ZODB, see the ZODB Wiki: >> http://www.zope.org/Wikis/ZODB/ >> >> ZODB-Dev mailing list - zodb-...@zope.org >> https://mail.zope.org/mailman/listinfo/zodb-dev >> > _______________________________________________ > For more information about ZODB, see the ZODB Wiki: > http://www.zope.org/Wikis/ZODB/ > > ZODB-Dev mailing list - ZODB-Dev@zope.org > https://mail.zope.org/mailman/listinfo/zodb-dev > > -- View this message in context: http://old.nabble.com/newbie-ZEO-first-try.--ConflictError.-tp26532984p26534826.html Sent from the Zope - ZODB-Dev mailing list archive at Nabble.com. _______________________________________________ For more information about ZODB, see the ZODB Wiki: http://www.zope.org/Wikis/ZODB/ ZODB-Dev mailing list - ZODB-Dev@zope.org https://mail.zope.org/mailman/listinfo/zodb-dev
