It's hard to follow what you're doing. It might help if you posted
*your* code, rather than the ZODB code.
But first, I suspect, as you do, that the C++ threads aren't playing
nice with the Python per-thread transaction management.
I suggest giving each connection it's own transaction manager:
>>> conn = db.open(transaction.TransactionManager())
>>> ... do some things
>>> conn.transaction_manager.commit()
As long only one thread is accessing the connection at a time, you
should be OK.
Jim
2010/6/8 Alberto Casado Martín <alberto.casado.mar...@gmail.com>:
>
> Sorry again , think i didn't confirm the inscription before sending the
> mail... :)
>
> 2010/6/8 Alberto Casado <alberto.casado.mar...@gmail.com>
>>
>>
>> I forgot one step in the code, sorry.
>>
>> El 08/06/2010, a las 02:08, Alberto Casado escribió:
>>
>> Hi all
>> I don't know if this is the list where I have to ask, if isn't it, sorry.
>> In the last weeks I am having a lot of problems trying to figure out how
>> ZODB should interact with a multithread app.
>> In short, basically the App is a GUI that receives data from sensors. It
>> is a distributed system, built with omniORB, when the info comes from the
>> sensors it is store in ZODB and it is shown in a GUI where can be modify by
>> an operator (human) and this changes are commited to ZODB and send back to
>> the sensor.
>> I have a connection for each thread, due to that sometimes the thread is
>> created in c++, I don't have the control of the pool. But i am pretty sure
>> that before any change is done, I create a new connection for this thread
>> (and also getting the root object).
>> Almost every time i try to commit to ZODB I have an error
>> Duplicate tpc_begin calls for same transaction
>> I have observed that when info comes from the sensors (one call, one
>> thread , I am dealing only with one message now) and I update the data ,
>> different objects (ZODB persistent classes), these distinct objects are
>> registered in several connections, so when I try to commit them, always end
>> up in the same error...
>> As I can see in the code, the first time goes fine, but the second is
>> going to fail always, because the transaction is assigned to the storage.
>> from _transaction.py:
>> def _commitResources(self):
>> # Execute the two-phase commit protocol.
>> L = list(self._resources)
>> L.sort(rm_cmp)
>> try:
>> for rm in L:
>> rm.tpc_begin(self)------- tpc_begin always with self.
>> for rm in L:
>> rm.commit(self)
>> self.log.debug("commit %r" % rm)
>> for rm in L:
>> rm.tpc_vote(self)
>> self._voted[id(rm)] = True
>>
>> from Connection.py.
>> def tpc_begin(self, transaction):
>> """Begin commit of a transaction, starting the two-phase
>> commit."""
>> self._modified = []
>> # _creating is a list of oids of new objects, which is used to
>> # remove them from the cache if a transaction aborts.
>> self._creating.clear()
>> self._normal_storage.tpc_begin(transaction)
>>
>>
>>
>>
>> From BasicStorage.py
>> def tpc_begin(self, transaction, tid=None, status=' '):
>> if self._is_read_only:
>> raise POSException.ReadOnlyError()
>> self._lock_acquire()
>> try:
>> if self._transaction is transaction:------------ the fisrt
>> time goes fine,but the second always fail
>> raise POSException.StorageTransactionError(
>> "Duplicate tpc_begin calls for same transaction")
>> self._lock_release()
>> self._commit_lock_acquire()
>> self._lock_acquire()
>> self._transaction = transaction------------
>> self._clear_temp()
>> This is killing me, I don't know if it is an error registering
>> modifications that are happening in one thread, to several connections and I
>> dont know why this is happening...
>> I someone can give me some clue...
>>
>> BR.
>> Alberto.
>> PD: sorry for my English.
>>
>>
>
> _______________________________________________
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>
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>
>
--
Jim Fulton
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