Pierangelo Masarati wrote:
I'd like to mention a different scenario, where proxy databases
deal with a mix of slow and fast targets. What we experienced is that
concurrency can be heavily penalized by this sort of mix of targets when
few threads are available, because inevitably operations affecting slow
targets eat up resources that remain idle in ldap_result() while they
could be used to deal with fast target related operations, while now
they have to remain pending. In some cases, we had to use up to 128
threads (we even experimented with 512) with big waste of system resources.
A solution could be to redesign the proxies so that request and response
are handled independently by different threads, using "client"
connections that detect activities on persistent connection handlers
towards the targets. Together with a customer, we quickly prototyped
something like this (back-aldap, standing for "asynchronous ldap"),
which is just a toy right now, but it showed some potential.
I remember thinking that we need to do this; the syncrepl consumer
certainly works better with this approach.
-- Howard Chu
Chief Architect, Symas Corp. http://www.symas.com
Director, Highland Sun http://highlandsun.com/hyc/
Chief Architect, OpenLDAP http://www.openldap.org/project/