Re: Random crash when sending USR2 + QUIT signals to Unicorn process

[Jeremy Evans <code@jeremyevans.net>]

On 07/14 09:16, Eric Wong wrote:
> Pere Joan Martorell <pere.joan@camaloon.com> wrote:
> > I suspect that the conflicting gem was 'sequel_pg' (sequel_pg
> > overwrites the inner loop of the Sequel postgres adapter row fetching
> > code with a C version. The C version is significantly faster than the
> > pure ruby version that Sequel uses by default), but given I didn't
> > remove these gems one by one I can't completely ensure that.
> > 
> > If the problem reemerges I'll keep you informed.
> > 
> > Thanks!! :)
> 
> Thanks for the info.  I've added Jeremy Evans, the author of
> sequel_pg to the Cc: even though I think he reads this list...
> 
> Anyways, I think I've spotted one potential bug in sequel_pg
> w.r.t. RB_GC_GUARD usage, and the fix is below:
> 
>   git clone https://github.com/jeremyevans/sequel_pg && cd sequel_pg
>   curl https://80x24.org/spew/20170714210918.3332-1-e@80x24.org/raw | git am
> 
> (more in-depth explanation is in the commit message)
> 
> Pere: perhaps you can give it a shot
> 
> Keep in mind I've only compile-tested this.  I didn't find
> automated tests in the code and I don't have a usable Postgres
> instance, at the moment.

Eric,

Thanks for this patch.  I'm not an RB_GC_GUARD expert, but the changes
look fine to me. The existing RB_GC_GUARD calls were added by me in
2012 to fix an earlier segfault.[1] This is the first reported
RB_GC_GUARD-related segfault in sequel_pg since then.

Pere, I would appreciate if you could test this patch and see if it
fixes your issue.  I will also test it and will release a new sequel_pg
version with this patch if it fixes the issue.

Thanks,
Jeremy

[1] https://github.com/jeremyevans/sequel_pg/commit/15edb132887d9b5292cad419fc7692ed5cd4b01b.diff