[asterisk-bugs] [JIRA] (ASTERISK-28171) res_resolver_unbound: DNS issue when under load, can't make outgoing calls

[Cyril Ramière (JIRA)]

    [ https://issues.asterisk.org/jira/browse/ASTERISK-28171?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=248699#comment-248699 ] 

Cyril Ramière commented on ASTERISK-28171:
------------------------------------------

Hi Sean,

Well, wouldn't saw that coming :)

A big thanks for the provided workaround, so we got rid of ubuntu's libevent, compile & install a new one then compile & install libunbound2 and everything seems to work as expected.

That was really a viscious issue... "fake libevent implementation" with a hard coded limit... really? ^^ 

Glad it was fixed in next ubuntu releases.

Maybe a quick note on the install guide for our fellows relying on Ubuntu 16.04LTS would be a nice attention since this issue is not generating any error messages while discarding calls.

Again, thanks for your help :) 

> res_resolver_unbound: DNS issue when under load, can't make outgoing calls
> --------------------------------------------------------------------------
>
>                 Key: ASTERISK-28171
>                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-28171
>             Project: Asterisk
>          Issue Type: Bug
>      Security Level: None
>          Components: Resources/res_resolver_unbound
>    Affects Versions: 15.4.0, 16.0.0, 16.6.1
>         Environment: Linux, Ubuntu 16.04 (kernel 4.4.0-1060-aws)
>            Reporter: Cyril Ramière
>            Assignee: Unassigned
>              Labels: pjsip
>         Attachments: asterisk.zip, console.log, fd.txt, locks.txt, taskprocessor.txt, threads.txt
>
>
> Hello,
> We have an issue with Asterisk, let me try to explain the setup and the problem:
> h5. Setup
> An instance on AWS (C5.2XLARGE) : 8CPU & 16GB RAM.
> Ubuntu 16.04, kernel 4.4.
> Tried with Amazon Linux 2 AMI and got same issue. 
> Only asterisk installed (compile from src, tested on v15.4.0 & 16.0).
> Using PJSIP (bundled).
> h5. The problem
> Problem is with outgoing calls (from US to our trunk), our trunk is set with an URL (so it uses DNS, that's very important).
> When Asterisk is processing hundreds of calls (400, 500), and we try to make an outbound call using our trunk, it doesn't work.
> We checked the configuration and everything seems fine, we replaced the instance & recompiled asterisk, same thing.
> We tested on the last Asterisk 16.0, same thing.
> We are running out of ideas, the instance is really big and can handle easily the load, if we use an IP instead of the DNS for our trunk, it works, so problem seems DNS related.
> We checked everything we can, there are no DNS issues on the instance, resolution is absolutely fine.
> I'm attaching the configuration that we use, and the outputs (console).
> There are some messages related to the unbound library.
> Ulimits are fine.
> Seems that realtime is not part of the issue, for the sake of simplicity I removed the realtime configuration and kept a light configuration.
> h5. Steps to reproduce
> Start asterisk
> Use SIPP to call extension 1000 with 400/500 calls and wait for the calls to be handled.
> Try to make an outgoing call through the "outgoing" endpoint
> Please tell me if you want more information/logs.



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