[GNC] Lightweight multi-user enhancement suggestion

[David G. Pickett]

 Kalpesh:
My suggestion will teach them, with lock files and messages if not by normal documentation, that they cannot use it that way!
I am familiar with callbacks, but in a multiuser system, I suppose callbacks might need to flow between users!  A remote common RDBMS might not support that, so gnucash might need to become cloud/server based except for clients for entry and display.  Still no free lunch!  :D
Best,
David P
    On Friday, July 17, 2026 at 06:00:13 AM EDT, Kalpesh Patel <kalpesh.patel at usa.net> wrote:   

 I don’t think multi-user is trivial to implement. Especially with something like this, everyone is going to jump on it and think that it has full fledge capabilities when it doesn't. 

In multi-user a robust controller is going to be needed that serializes in coming updates requests for data and then keeps track to perform call backs to refresh.

-----Original Message-----
From: David Carlson <david.carlson.417 at gmail.com> 
Sent: Thursday, July 16, 2026 8:51 PM
To: David G. Pickett <dgpickett at aol.com>
Cc: Jim Passmore <jim at passmore4.com>; Gnucash Users <gnucash-user at gnucash.org>
Subject: Re: [GNC] Lightweight multi-user enhancement suggestion

I think that this would open up the program to another way to corrupt the data.  The developers are already working toward a goal of making the program truly fit in a multi-user database format.  I would prefer trying to accelerate progress to that goal.

On Thu, Jul 16, 2026 at 3:47 PM David G. Pickett via gnucash-user < gnucash-user at gnucash.org> wrote:

>  The check is just based on a boolean variable set when the lock file 
> is removed.  If set, check for a lock file of another user and then 
> check if the primary file is now different.  Checking a boolean is the 
> cost of a 1 byte fetch.
>
> Other users arriving can set a lock file and create a new version as 
> usual, but of course will set the boolean and remove that lock file 
> after creating a new primary version with a save.
>
> I suppose that the next modifier of the data should write a new 
> version, as now, not rewrite the primary version, even if they 
> authored the current primary version with a save.  We don't want to get into a race condition.
> There might need to more checking of the lock file, moving that check 
> to where a modification has occurred.
>
> The general idea is that, with timed auto save, the file is quiescent 
> a lot of the time, and the lock file is not necessary.  If you reboot 
> without giving gnucash a normal termination, you will generally have 
> to accept that the lock file is irrelevant, although for no-timed-save 
> people, it may indicate a loss of some transactions.  Maybe timed save 
> should be mandatory, and only the duration configured?
>    On Thursday, July 16, 2026 at 03:49:35 PM EDT, Jim Passmore < 
> jim at passmore4.com> wrote:
>
>
> On Wed, Jul 15, 2026 at 11:34 AM David G. Pickett via gnucash-user < 
> gnucash-user at gnucash.org> wrote:
>
> It occurred to me that, once a save has been completed, gnucash could 
> delete the lock file.  This would allow either another user of 
> networked files or a botch run for finance quotes to update the file.  
> If the running original gnucash goes to modify his memory or display a 
> new page or report, a flag can tell it that it deleted the lock, and 
> so check the age of the file
>
> Mulling it over...* How often should it check for the presence of the 
> lock file?  Seems like checking the file system before every action 
> could drag down responsiveness.  (And if too infrequently, and you'll 
> make a change not knowing the lock file has been created.)* When 
> checking file "age" I assume it would use a time stamp?  What happens 
> if the different computers don't have their clocks synchronized?  I've 
> even had time stamp craziness on a single computer when dual-booting 2 
> OS's...one assumes the time on the BIOS clock was local, and the other 
> assumes BIOS is UTC, so they were hours off.
> -- Jim
>
>
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--
David Carlson