CFLOCK and session vars

[Guest]

I am building a multiuser site with session vars. I understand the need for exclusive locking when writing session vars, but am a little confused when it comes to reading them. I have the need to use certain session vars within SQL queries, etc. I do need to use exclusive here as well, right? Also, Is this bad?



I'd rather not have a hundred cflock statements within my CFC functions, etc.

[Newsgroup_User]

> I am building a multiuser site with session vars.

Which CF version?


> I understand the need for
> exclusive locking when writing session vars,

One hasn't had to - intrinsically - do this since CF5.

Read the docs regarding when to lock shared-scope data:

http://livedocs.adobe.com/coldfusion/8/htmldocs/help.html?content=sharedVars_20.html


> Also, Is this
> bad? <cflock scope='session' timeout='30' type='exclusive'> <cfset mySess =
> session /> </cflock>

This will achieve little, as it will simply create a reference to the
session scaope, rather than a copy. All you're doing is referring to the
same shared-scope data (with the same potential issues) via a different
variable name.

On the whole, locking shared-scope data is far less of a concern since CF5
than it used to be.

If you want to do some reading, read the doc I pointed you to, and Google
CFLOCK. This conversation has been well documented several times in the
past (and at least ocne on these forums within the last month or so).

--
Adam

[Guest]

This cannot be true. I am using CF8. Without an exclusive lock on both reading and writing my application's session variables I have witnessed my users getting their sessions mixed up.

Example: My users (average of 150 concurrent) all get content generated from a single SQL view, and we pass in their userId using cfqueryparam. If I do not wrap that query in an exclusive session lock, users randomly see results that are not meant for their eyes.

[Dinghus]

That sounds like a problem with the variable scoping.

[Newsgroup_User]

> This cannot be true. I am using CF8. Without an exclusive lock on both
> reading and writing my application's session variables I have witnessed my

Session variables aren't shared *between users*. They're specific to a
user. The only time you're going to be getting contension with a session
variable is when a single user has two browser windows open hitting the
same site. If you've got some weird session bleeding between different
users, then <locking the session scope isn't going to help.

You're problem is something else, and your locking strategy is at best
dealing with it coincidentally. Which should be a bit of a concern...

--
Adam

[Newsgroup_User]

> contension

Oh dear.

"contention".

--
Adam

[Newsgroup_User]

> You're

Groan. I give up.

:-(

--
Adam

[BKBK]

Emadsen wrote:
If I do not wrap that query in an exclusive session lock, users randomly see results that are not meant for their eyes.

The answer might simply be to rename a variable into session.someResult. In fact, you could even do this:

<cfquery name="session.getOrderItem">