On Monday 11 April 2016 18:12:43, Eric Covener wrote:
> On Mon, Apr 11, 2016 at 4:59 PM, <bugzi...@apache.org> wrote:
> > ServerLimit >= 10 * MaxRequestWorkers / ThreadsPerChild
>
> Hi Stefan -- I am curious -- prior to the recent patches, just
> having the extra capacity in ServerLimit didn't help / didn't help
> as much?
No, without the patches attached to the PR, ServerLimit does not play
any role for this issue. Only the scoreboard entries up to
(MaxRequestWorkers / ThreadsPerChild) will ever be used.
The state in 2.4 is that scoreboard entries of processes where some
threads have already terminated would get re-used, but there is no
code that terminate threads before the whole process terminates.
In trunk, I have added logic to terminate threads as soon as possible
during graceful finishing of a process. But the reason for that is
that I want old processes to use as few resources as possible. I am
not sure that new processes re-using the scoreboard entries of those
threads is a good idea. In the worst case, you could get
ThreadsPerChild processes that each use one worker slot in the
scoreboard area of a single process.
Maybe it would be better to remove the logic to re-use scoreboard
slots of processes which have already terminated some threads.
Instead, one could use the scoreboard area abore (MaxRequestWorkers /
ThreadsPerChild) more aggressively, and maybe even allocate some
additional slack space at startup. There could be these config knobs:
- the max number of fully active processes (ServerLimit)
- the max number of gracefully finishing processes ("OldServerLimit"?)
- what to do if OldServerLimit is reached during a graceful restart:
* reduce the max number of fully active processes accordingly
* kill off old processes
- what to do if OldServerLimit during normal operation:
* stop doing idle-cleanup of fully active processes [X]
* kill off old processes
Hmm. Now that I think of it, I think we should really do [X] if there
are too many old processes. The only question is how to define too
many.
Any thoughts?
