[undertow-dev] Too many open files: Exception accepting request, closing server channel TCP server (NIO)

[Flavia Rainone]

Can someone provide a reproducer for this error?

As for the old version of XNIO, it will be upgraded in Undertow 2.1.0.Final.

On Mon, Mar 2, 2020 at 8:47 PM Stuart Douglas <sdouglas at redhat.com> wrote:

> Hmm, maybe this is a bug in the HTTP/2 close code then, and somehow the
> connection is not being closed if the client hangs up abruptly. I had a
> quick look at the code though and I think it looks ok, but maybe some more
> investigation is needed.
>
> Stuart
>
> On Tue, 3 Mar 2020 at 03:41, Nishant Kumar <nishantkumar35 at gmail.com>
> wrote:
>
>> Yes, i have no control on client side. I am using HTTP2. I have tried
>> increasing open file limit to 400k but that consumes all memory and system
>> hangs. I will probably try to put a nginx in front of Undertow and test.
>>
>> setServerOption(UndertowOptions.ENABLE_HTTP2, true)
>>
>> On Mon, Mar 2, 2020, 7:48 PM David Lloyd <david.lloyd at redhat.com> wrote:
>>
>>> On Mon, Mar 2, 2020 at 7:56 AM Stan Rosenberg <stan.rosenberg at acm.org>
>>> wrote:
>>> >
>>> > Stuck in CLOSE_WAIT is a symptom of the client-side not properly
>>> shutting down [1].
>>>
>>> I would partially disagree.  In the article you linked: "It all starts
>>> with a listening application that leaks sockets and forgets to call
>>> close(). This kind of bug does happen in complex applications."  This
>>> seems to be essentially what's happening here: the server isn't
>>> completing the connection (for some reason), stranding the socket in
>>> `CLOSE_WAIT`.
>>>
>>> We can't assume that the client is abandoning the connection after
>>> `FIN_WAIT2` (the titular RFC violation); if the server stays in
>>> `CLOSE_WAIT`, then even if the client dutifully stays in `FIN_WAIT2`
>>> forever, the resolving condition still needs to be that the server
>>> shuts down its side of the connection.
>>>
>>> This diagram is a useful visual aid, mapping TCP states to the XNIO
>>> API:
>>> https://www.lucidchart.com/publicSegments/view/524ec20a-5c40-4fd0-8bde-0a1c0a0046e1/image.png
>>>
>>> --
>>> - DML
>>>
>>> _______________________________________________
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> undertow-dev at lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/undertow-dev



-- 

Flavia Rainone

Principal Software Engineer

Red Hat <https://www.redhat.com>

frainone at redhat.com
<https://www.redhat.com>
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