launchpad-dev team mailing list archive

[Gary Poster <gary.poster@xxxxxxxxxxxxx>]

On Jan 11, 2010, at 2:59 PM, Guilherme Salgado wrote:

> On Fri, 2010-01-08 at 09:27 -0200, Guilherme Salgado wrote:
>> On Thu, 2010-01-07 at 15:43 -0500, Francis J. Lacoste wrote:
>>> On January 7, 2010, Guilherme Salgado wrote:
>>>> As I explained earlier, to make the read-only mode switching
>>>> transparent, I turned the main_master/slave config variables into
>>>> properties of DatabaseConfig, which return either rw_main_* or
>>>> ro_main_*, depending on the mode we're on.
> 
> When I came up with the plan above I think I blindly assumed the next
> time a request kicked in after a mode switch, it would re-connect to the
> database, thus connecting to the appropriate one. That doesn't happen;
> the connections to the database will be reused (and thus stay connected
> to the DB that was appropriate when they were created) until they are
> explicitly closed or left marked as dead.
> 
> I can't think of an easy way to close a connection at the beginning of a
> request (as we don't want to switch modes mid-request) and only once for
> each connection. Do you guys have any ideas?

Can we check to explicitly close connections at the end of a request?

> I'm starting to think it'd be better to have the switch require the
> read-only.txt file be put in place plus the server restarted, and then
> later we can work on making it work without a restart. But I wonder if
> just replacing the config changes (currently needed to switch) with the
> read-only.txt file is a significant win to the LOSAs?

I don't think it is.  Making a restart not required is the win we are after.

Gary