4:32 a.m.
On Thu, Feb 22, 2018 at 4:04 PM, Brad Wood <bdw429s(a)gmail.com> wrote:
I'm looking for a bit of understanding on just how Undertow
handles large
numbers of requests coming into a server. Specifically when more requests
are being sent in than are being completed. I've been doing some load
testing on a CFML app (Lucee Server) where I happen to have my io-threads
set to 4 and my worker-threads set to 150. I'm using a monitoring tool
(FusionReactor) that shows me the number of currently executing threads at
my app and under heavy load I see exact 150 running HTTP threads in my app
server, which makes sense since I have 150 worker threads. I'm assuming
here that I can't simultaneously process more requests than I have worker
threads (please correct if I'm off there)
So assuming I'm thinking that through correctly, what happens to
additional requests that are coming into the server at that point? I
assume they are being queued somewhere, but
- What is this queue?
The queue is in the XNIO worker (although if you want you could just use a
different executor which has its own queue).
- How do I monitor it?
XNIO binds an MBean that you can use to inspect the worker queue size.
- How big can it get?
It is unbounded, as rejecting tasks from the worker is very problematic in
some
circumstances. If you want to limit the number of concurrent requests
use the io.undertow.server.handlers.RequestLimitingHandler
- Where do I change the size?
- How long do things stay in there before sending back an error to the
HTTP client?
If you use the RequestLimitingHandler this is configurable. It has its own
queue
with a fixed size, and a configurable timeout.
- Can I control what error comes back to the HTTP client in that
scenario?
You can using io.undertow.server.handlers.RequestLimit#setFailureHandler
- If I'm using an HTTP/S and AJP listener, do they all share the same
settings? Do they share the same queues?
In general yes. You could give each listener its own limiting handler with
its own
queue if you wanted by explicitly setting the listeners root
handler, however in general they will all just use the same handler chain.
Stuart
I've done a bit of Googling and reviewed some docs but
haven't quite found
any definitive information on this, and a lot of info I found was about
Wildfly specifically so I wasn't sure how much of it applied.
Thanks!
~Brad
*Developer Advocate*
*Ortus Solutions, Corp *
E-mail: brad(a)coldbox.org
ColdBox Platform: http://www.coldbox.org
Blog: http://www.codersrevolution.com
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