Re: [Monotone-devel] Time to create a monotone cluster?

[Timothy Brownawell]

On Sat, 2007-03-31 at 15:12 +0800, Grahame Bowland wrote:
> I can easily enough start running a public monotone server, but
> there's one catch - can anyone think of a solution?
> 
> I've got viewmtn running, and a number of long-lived mtn processes
> reading from the database. I've recently modified viewmtn to notice
> when the db file mtime changes and restart the mtn processes.
> 
> The trouble is updates; these lock the database, and the readers can't
> access it. People start getting error pages when accessing the web
> page. What I'm currently doing is:
>   - copy the database file to a temporary file
>   - pull into that file
>   - do a atomic rename() to replace the old database file
> 
> This is quite transparent to any running mtn processes, as they just
> keep using the old database until stopped. However, it's slow and more
> than a little crude - and it will suck horribly when trying to deal
> with regular updates.
> 
> I can't think of a better solution short of some sort of union
> filesystem that allows me to have the temporrary db file be based upon
> the original, removing the slowness of the copy. That could work, but
> it's still pretty horrible for anyone else wanting to run a viewmtn
> server..

I can't think of any other immediate solutions, but a longer-term
solution (that I've been kinda-sorta working on for a while now) would
be to have 'mtn serve' also serve automate stdio over network
connections.

-- 
Timothy

Free (experimental) public monotone hosting: http://mtn-host.prjek.net