https://bugs.openldap.org/show_bug.cgi?id=10617

Issue ID: 10617 Summary: Add an option to throttle when qtime exceeds a threshold Product: OpenLDAP Version: 2.7.0 Hardware: All OS: All Status: UNCONFIRMED Keywords: needs_review Severity: enhancement Priority: --- Component: slapd Assignee: bugs@openldap.org Reporter: hyc@openldap.org Target Milestone: ---

The first sign that a server is overloaded is that ops start spending longer time being queued before being executed. If the incoming load continues, the qtimes will continue growing. As such, an overload can be short-circuited before it gets completely out of hand by rejecting operations once their qtime exceeds a given threshold.

We should add a config keyword to set a qtime threshold. When an operation hits the threshold it should be rejected.

Note that we already implemented a feature like this experimentally for a private user, so we already know it is effective. In practice, qtimes on a healthy server are much less than 1msec. A qtime of 1msec would already indicate an overload condition.