Please sign in to comment.
Restore our priority-inversion-prevention code with deferreds
Back when deferred_cb stuff had its own queue, the queue was always executed, but we never ran more than 16 callbacks per iteration. That made for two problems: 1: Because deferred_cb stuff would always run, and had no priority, it could cause priority inversion. 2: It doesn't respect the max_dispatch_interval code. Then, when I refactored deferred_cb to be a special case of event_callback, that solved the above issues, but made for two more issues: 3: Because deferred_cb stuff would always get the default priority, it could could low-priority bufferevents to get too much priority. 4: With code like bufferevent_pair, it's easy to get into a situation where two deferreds keep adding one another, preventing the event loop from ever actually scanning for more events. This commit fixes the above by giving deferreds a better notion of priorities, and by limiting the number of deferreds that can be added to the _current_ loop iteration's active queues. (Extra deferreds are put into the active_later state.) That isn't an all-purpose priority inversion solution, of course: for that, you may need to mess around with max_dispatch_interval.
- Loading branch information...
Showing with 80 additions and 23 deletions.