UDNS issues at high query rate

[Abhijit Pandey]

Ok,

The crash for case 2) is at

udns_resolver.c:614: dns_end_query: Assertion `ctx->dnsc_nactive > 0' failed.

Abhijit




On Tue, Aug 4, 2009 at 7:44 PM, Abhijit Pandey<abhijpandey at gmail.com> wrote:
> Hi Michael,
>
>
> I needed some help in isolating the following issues I am facing, when
> I send the queries at a high rate.
>
>
> The query rate is around 1000/second. The default resolver
> context(NULL) is opened to which queries are continually submitted.
> Have a forever thread for the ioevent.
>
> 1) The queries get submitted, but the responses(dnscb) does not get called.
>     As a result those queries are not freed.
>
>
> 2) Submitting the query at a high rate, result in a lot of dns errors.
>    I see the following
>
>         unable to lookup A record for
> ikrnlmlmc3kvti31ab6ahtgt85.prpt.trmp.com: temporary failure in name
> resolution
>         unable to lookup A record for
> ikrnlmlmc3kvti31ab6ahtgt85.prpt.trmp.com: temporary failure in name
> resolution
>         unable to lookup A record for
> 9pljvmjeqwlqdue6rrahw6799v.prpt.trmp.com: temporary failure in name
> resolution
>
>   After a while I see a crash in the library.
>
> *** glibc detected *** malloc(): memory corruption: 0x30545838 ***
> Program received signal SIGABRT, Aborted.
>
>
> 3) When I change the IP address in resolv.conf, when queries are being
> submitted to the resolver.
>     I do a dns_init. This sometimes also causes a assertion failure
>
> udns_resolver.c:862: dns_submit_dn: Assertion
> `(ctx->dnsc_udpsock >= 0)' failed.
> Program received signal SIGABRT, Aborted.
>
> Let me know how should I fix it.
>
> I could probably rate limit, the queries being submitted if they fix the issue.
> Let me know some numbers in that case.
>
> Thanks,
> Abhijit
>