<div dir="ltr">Hi, thanks for you answer, i'm sorry I forgot to notice that my store object is retrieved from an helper function which handle one store instance by thread : Database = create_database("mysql://"+<div dir="ltr">ServerConfig.dbUser+":"+ServerConfig.dbPassword+"@"+ServerConfig.dbHost+"/"+ServerConfig.dbName) LocalStoreHolder = threading.local() def GetStore():     global LocalStoreHolder     global Database         if (not hasattr(LocalStoreHolder,"store")):         LocalStoreHolder.store = Store(Database)             log.msg("Returning store instance :%s for thread : %s"%(LocalStoreHolder.store,threading.currentThread().getName()))     return LocalStoreHolder.store The problem I think is there is no lock put on the selected row after the first thread has read it - On Mysql it'is handled with running the query with "SELECT ... FOR UPDATE"  or "SELECT ... LOCK IN SHARE MODE" Any idea on how to make storm using this behaviour ? Thanks</div> <div class="gmail_quote">2008/9/4 Jamu Kakar <<a href="mailto:jkakar@kakar.ca">jkakar@kakar.ca</a>> <blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> Hi,<div class="Ih2E3d"> NeedBenzyn NeedBenzyn wrote: <blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> I'd like to know what would be the proper way in storm to execute that kind of code on a multithreaded server (acessing MySql server InnoDb tables):    def bankOperation():        account = store.find(BankAccount,BankAccount.id == 1).one()        if account == None:            return        #Simulate some processing        waittime = random.random()*4        time.sleep(waittime)        account.value = account.value + 100        store.flush()                store.commit() ==> If I have more than one thread executing that code data become inconsistent. </blockquote> </div> You need to make sure you use one Store per-thread.  Something like this (untested) code should work: def bank_operation(store, id):    account = store.find(BankAccount, BankAccount.id == id).one()    if account:        account.value += 100 def run_thread():    store = Store(create_database(...))    try:        bank_operation(store, 1)    except:        store.rollback()        raise    else:        store.commit() Storm automatically uses transactions, so you shouldn't have to worry about locking tables and such (though this may not be true for SQLite). Thanks, J. </blockquote></div> </div>