Combating nginx 499 HTTP responses during flash traffic scenario

Eric Wong normalperson at
Thu Nov 29 20:41:00 UTC 2012

Tom Burns <tom.burns at> wrote:
> So we just finished the US Black Friday / Cyber Monday weekend running
> unicorn forked with the last version of the patch I had sent you.  It
> worked splendidly and helped us handle huge flash sales without
> increased response time over the weekend.
> Whereas in previous flash traffic scenarios we would see the number of
> HTTP 499 responses grow past the number of real HTTP 200 responses,
> over the weekend we saw no growth in 499s during flash sales.
> Unexpectedly the patch also helped us ward off a DoS attack where the
> attackers were disconnecting immediately after making a request.

That is absolutely wonderful to hear.  I've amended your commit message
with the above quoted portion.

> I've attached the patch again, with your last comments addressed.  Let
> me know if there's anything else.
> Thanks again for your help in this matter.

Thank _you_ for the patch, documentation and most importantly:
testing with real traffic.

I fixed up some minor line-wrapping, signed-off, and added your
quote above to the commit message.  Pushed as
commit 5c700fc2cf398848ddcf71a2aa3f0f2a6563e87b
to git://

I'll tag and push a 4.5.0.preview1 gem soon

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