(ITS#4188) long-running tasks and back-config

[hyc@OpenLDAP.org]

Full_Name: Howard Chu
Version: 2.3.12
OS: 
URL: ftp://ftp.openldap.org/incoming/
Submission from: (NULL) (24.126.120.178)
Submitted by: hyc


Submitting a modify request to back-config while e.g. syncprov_qtask is active
will prevent anything else from running until the syncprov_qtask completes. If a
large number of database writes have occurred and the syncrepl persistent
searches have a large backlog this can take a very long time. It may be better
to have syncprov check to see if the thread pool is pausing, and let go and
reschedule itself.

A very long search would also be a problem.

Suspending those threads and resuming them later isn't a good idea if the config
changes eliminate those threads' underlying data...