[ZODB-Dev] How to update an object in a multithreading application?

[Sebastian Wain]

I am updating an item in a separated thread but when it finishes the new
value is not updated in the same object in the main thread.

 

In the example below root['counter'] starts in 0, is incremented in the new
thread but it remains in 0 in the main thread.

 

#!/usr/bin/python

 

from ZODB.FileStorage import FileStorage

from ZODB.DB import DB

from BTrees.OOBTree import OOBTree

import transaction

from threading import Thread

import persistent

 

class MyThread(Thread):

   def __init__(self, db):

      Thread.__init__(self)

      self.db = db

 

   def run(self):

      self.connection = self.db.open(transaction.TransactionManager())

      self.root = self.connection.root()

 

      print "Starting thread"

      self.connection.transaction_manager.begin()

      self.root["counter"] += 1

      self.connection.transaction_manager.commit()

      print "self.root['counter'] =", self.root['counter']

 

 

filename = 'test.fs'

 

storage = FileStorage(filename)

db = DB(storage)

connection = db.open()

 

root = connection.root()

if 'counter' not in root:

   transaction.begin()

   root['counter'] = 0

   transaction.commit()

 

thread = MyThread(db)

thread.start()

 

thread.join()

 

print "*** After ***"

print "root['counter'] =", root['counter']

 

 

Thanks,

Sebastian

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