[THIN] Re: Quickbooks 2008 on CAE and W2k3

Well since I didn’t know what either a mutex or a semaphore was I found this and share it here:

 

http://geekswithblogs.net/shahed/archive/2006/06/09/81268.aspx

 

 

Mutex vs. Semaphore, what is the difference?

The Toilet Example  (c) Copyright 2005, Niclas Winquist ;)

 

 

Mutex:

 

Is a key to a toilet. One person can have the key - occupy the toilet - at the time. When finished, the person gives (frees) the key to the next person in the queue.

 

Officially: "Mutexes are typically used to serialise access to a section of  re-entrant code that cannot be executed concurrently by more than one thread. A mutex object only allows one thread into a controlled section, forcing other threads which attempt to gain access to that section to wait until the first thread has exited from that section."

Ref: Symbian Developer Library

 

(A mutex is really a semaphore with value 1.)

 

Semaphore:

 

Is the number of free identical toilet keys. Example, say we have four toilets with identical locks and keys. The semaphore count - the count of keys - is set to 4 at beginning (all four toilets are free), then the count value is decremented as people are coming in. If all toilets are full, ie. there are no free keys left, the semaphore count is 0. Now, when eq. one person leaves the toilet, semaphore is increased to 1 (one free key), and given to the next person in the queue.

 

Officially: "A semaphore restricts the number of simultaneous users of a shared resource up to a maximum number. Threads can request access to the resource (decrementing the semaphore), and can signal that they have finished using the resource (incrementing the semaphore)."

Ref: Symbian Developer Library

 

 

 

Steve Greenberg

Thin Client Computing

34522 N. Scottsdale Rd D8453

Scottsdale, AZ 85266

(602) 432-8649

www.thinclient.net

steveg@thinclient.net

 

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From: thin-bounce@freelists.org [mailto:thin-bounce@freelists.org] On Behalf Of Rick Mack
Sent: Thursday, September 25, 2008 7:47 PM
To: thin@freelists.org
Subject: [THIN] Re: Quickbooks 2008 on CAE and W2k3

 

Hi Gehan,

 

Quickbooks 2008/2007 uses a global mutex as a semaphore so that only one instance of QB will run.

 

I specificall covered how to handle the QB global mutex issue in my talk at Briforum 2008. You should be able to get my video from http://www.briforum.com/BriForum-2008-Chicago/session.asp?id=338

 

regards,

 

Rick

 

--
Ulrich Mack
Quest Software
Provision Networks Division

On Tue, Sep 23, 2008 at 3:27 PM, <Gehan.DeSilva@rsmi.com.au> wrote:

Hello

Im most curious about this also as i have not yet been able to get this going.

Nick when you run Quickbooks with multiple users at the same time does it throw a message  "Quickbooks is already running"

Regards

____________________________________________________

Gehan De Silva