On 20.01.2019 19:52, Hallvard Breien Furuseth wrote:

Can cn=config have 2 lock levels? That fixes this ITS (my ldapwhoami hang) without introducing cn=config failures.

The outer lock serializes cn=config ops including the indexer. Other ops do not lock it.  The inner lock blocks slapd like cn=config does now, and should only be held briefly.  Always hold the outer lock when taking the inner lock.

Correction again: while taking and holding the inner lock. Except non-config ops.

Also, the inner lock could be taken and released several times during a config op when feasible.  That might improve non-config op latency, for the price of slower config ops.