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

[Sean Bright (JIRA)]

    [ https://issues.asterisk.org/jira/browse/ASTERISK-28171?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=248507#comment-248507 ] 

Sean Bright commented on ASTERISK-28171:
----------------------------------------

{{core show fd}} is only going to show a maximum of 1024 files, even if more are open. When this occurs again, can you run the following commands and share the output with us:

{noformat}
find /proc/`pidof asterisk`/fd | wc
cat /proc/`pidof asterisk`/limits
{noformat}

> 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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