Re: nsd: remote.c:2307: daemon_remote_process_stats: Assertion `s->in_stats_list' failed.

Hi Ask,

On 15/02/2019 06:39, Ask Bjørn Hansen wrote:
> Hi everyone,
>
> Recently some of my nsd installations started crashing every so many days (or weeks?) with:


This failure was reported to me before, and then I could not find it. 
Could not reproduce and code inspection shows it should not really be
possible.  With that I mean, that the code-paths that go to that
assertion all have the boolean turned on.  When that item is removed
from the list the boolean is turned off.  The only explanations I have
left are random heap corruption or somehow the list management does not
work right. This could happen if the item was in the list twice.  But
that is also not possible, both by this boolean and because only one
command per nsd-control stream.  So I am stymied at the issue; looks
like the code paths involved in having that linked list mismanaged are
all not possible.

Some runs in a memory checker like valgrind also show no issues. And
that is what I would ask for; some way to reproduce, or runs in a memory
checker like valgrind or gcc's libasan (that might catch the issue
before it becomes an assertion failure, eg. deleted element still in use
or something).  Is that is not possible; I guess I could try to make
debug-versions of the code for people that have it; some sort of
lighter-weight debug code to get more information on this issue, lighter
than valgrinds speed slowdown. But I am not sure what it would need to
check for.

Best regards, Wouter


>
> nsd: remote.c:2307: daemon_remote_process_stats: Assertion `s->in_stats_list' failed.
>
> I am using the 4.1.24-2.el7 build on CentOS 7.
>
> I haven’t been able to reproduce it. The servers are doing pretty light duty (<1000 qps) and rarely reloading configs.  “nsd-control stats_noreset” runs once or twice a minute (from a prometheus exporter).
>
> Is this a known problem in 4.1.24 or am I doing something goofy?
>
>
> Ask
>
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