On 1/21/19 7:49 PM, Ondřej Kuzník wrote: > Except there are no locks as you know being the author of parts of > code that deals with what I'm about to outline anyway: > > Whenever a cn=config op is about to be processed, a pause is requested. > That tells worker threads to stop picking up new work and waits until > they're all quiet. The indexing task is run by one of these worker > threads. Duuh, right. I got stuck looking for what's special about the indexing task and couldn't find it:-( I need to make it special. So, let tasks declare their expected speed until finish or between pausechecks. At FAST=1 (default) and SLOW=0. A pause only stops tasks with speed < ltp_pause. In thread_pool_pause(), replace the WANT_PAUSE stage with while (++ltp_pause <= max speed) { wait until no more tasks with speed < ltp_pause; } Then fast tasks should breeze past slow ones when preparing to pause. Until all threads have slow tasks, anyway. To mitigate that, we'd need to predeclare the speed when submitting a task, and limit the number of parallel slow tasks. pool_submit() could stash the rest in a "slow queue" instead of submitting. But I don't want to go there yet.