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From Stefan Eissing <stefan.eiss...@greenbytes.de>
Subject Re: MinSpareThreads lower bound calculation and docs
Date Thu, 23 Jun 2016 13:05:21 GMT
I am lurking with interest, but am no expert to answer your question. 

> Am 23.06.2016 um 14:55 schrieb Luca Toscano <toscano.luca@gmail.com>:
> 
> 
> 
> 2016-06-18 11:53 GMT+02:00 Luca Toscano <toscano.luca@gmail.com>:
> Hi Apache devs! 
> 
> I have a question for you about the following users@ email thread:
> 
> - https://lists.apache.org/thread.html/ba26440a53773426e29296569bec17692c77a4a3bd07e8b5331474c4@1464703063@%3Cusers.httpd.apache.org%3E
> 
> This one is about Yann's fix for the MinSpareThreads lower bound calculation for worker/event:
http://svn.apache.org/viewvc?view=revision&revision=1737447
> 
> I was able to explain how it works in case of bucket = 1, but I have doubts when buckets
> 1. I've read event/worker code and IIUC:
> 
> 1) min_spare_threads = threads_per_child * (num_buckets - 1) + num_buckets
> 2) max_spare_threads = min_spare_threads + threads_per_child * num_buckets
> 3) idle_spawn_rate controls the amount of new children created in each perform_idle_server_maintenance
run.
> 4) perform_idle_server_maintenance is called per bucket and calculates max|min_spare_threads
accordingly.
> 
> Rick's question in the email thread is about what happens when, with two buckets and
two processes for example, httpd reaches 50% of idle threads. I made some calculations and
an extra process should be indeed created, but then killed because of the max_spare_threads
limit. Is it going to keep creating/destroying child processes or does idle_spawn_rate prevents
it? 
> 
> Final goal would be to add notes in (Min|Max)SpareThreads documentation to warn users
about the (good) side effects of setting ListenCoresBucketRatio (there is a reference in the
trunk doc but very generic, it would be great to have more details IMHO).
> 
> 
> Anyone? :)
> 
> Thanks!
> 
> Luca 


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