Re: refreshAndPersist speed

[Howard Chu <hyc@symas.com>]

Leigh Porter wrote:
> Hiya,
>
> I would like to use refreshAndPersist between a master and slave but 
> my application uses
> a load balancer that round-robins ldap requests between a master and 
> slave server. I need to
> write to LDAP on the master but the read could be from any server.
>
> The time between a write and read could be sub second so I need the 
> master and slave to be in
> sync in a similar timeframe.
>
> Will syncrepl refreshAndPersist achieve this kind of instantanious 
> update of the slaves?
Yes and no. An individual update can propagate instantaneously. However, 
the current syncrepl client uses only a single thread to pull updates 
from the master, while the master can perform updates in many threads at 
once. As such, if there is a burst of write activity on the master, 
there will be an increasing lag of updates being processed on the slave. 
In the future we'll look into making the syncrepl client multi-threaded 
to address this shortcoming.

--
 -- Howard Chu
 Chief Architect, Symas Corp.  http://www.symas.com
 Director, Highland Sun        http://highlandsun.com/hyc
 OpenLDAP Core Team            http://www.openldap.org/project/