<quote who="TechnoSophos">
On the conn_max_pending and conn_max_pending_auth params, what exactly is a "pending request"? Is this a request that slapd has not yet processed? For example, is a search request "pending" if slapd is in the process of evaluating it, but has not yet returned?
Yes.
As per slapd.conf(5):
conn_max_pending <integer>
Specify the maximum number of pending requests for an anonymous session. If requests are submitted faster than the server can process them, they will be queued up to this limit. If the limit is exceeded, the session is closed. The default is 100.
conn_max_pending_auth <integer>
Specify the maximum number of pending requests for an authenticated session. The default is 1000.