Ok as Sean said, on its own that doesn cause a race condition. So no thats
true.
But, lets say somewhere else in the code you require that same variable for
other reporting. And in the meantime of you begining to do the reporting,
that variable changes. Hence a race conditon has occured.
The argument is not about one variable on its own, as stated the orignal
Author has a CFC stored inside a session variable, this is a classic exmple
that data is changing when he is reading the data out of the CFC, so when
this occurs it is a race condition that is happening.
Forget the one line hit count, as stated on its own and even Ben said that
but if you are worried about a race condition lock it and thats what is
happening here.
I am not interested in anyone saying that one set is going to cause a race
condition, I am more interested in the problem put forward and I am sorry to
say that cflock is required under these circumstances.
If anyone else wants to debate the ins and outs of race conditions then take
it offline, if however you want to discuss the problem this user is having
then so pist away, but I will stand by the statement I made this is a race
condition scenario and it should be treated as such and locked.
On 4/15/07, Jochem van Dieten <[EMAIL PROTECTED]> wrote:
>
> Andrew Scott wrote:
> >
> > Thats what I mean, best practice says use cfqueryparam, and every
> document
> > you read regardless of cfmx 5.0, 6.0, 7.0 says when writing to a
> variable
> > you will have a race condition.
>
> Just because you can have a race condition doesn't mean you will have a
> race condition.
>
>
> > Now I can't name the version I tested this on, but I followed one of the
> > articles directions on how a race condition will work. And you know
> what, it
> > proves that even this version of Coldfusion needs cflock around perstant
> > variable writes.
>
> No it doesn't. It proves that CF needs locking to prevent race
> conditions with some code constructs. It does not prove that CF needs
> locking with all writes to shared variables.
>
>
> Let me give you the simplest possible example. Let's suppose I have the
> following code in my onRequestStart to get a timestamp with a timezone
> compensation:
> <cfset session.lastHit = DateAdd('h', -1, Now())>
>
> I can use this variable to display the following to the user:
> <cfoutput>
> Last session activity as #session.lastHit#
> </cfoutput>
> This works lock-free without any problems.
>
> I can also use this variable to display the following to the user:
> <cfoutput>
> Page requested at #session.lastHit#, generated in #timer# ms.
> </cfoutput>
> This will show incorrect information in case of overlapping requests.
>
>
> Race conditions depend just as much on the meaning you give to a
> variable when reading it, as on the timing of the writing.
>
> Jochem
>
>
>
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