Nginx forum returns 502 (2014-03-25T08:13Z)

Jim Ohlstein jim at
Wed Mar 26 14:11:57 UTC 2014


On 3/26/14, 9:56 AM, B.R. wrote:

> I do not know if those 502 are directly tied to some IPv6 request, since
> I have both v4/v6 connectivity. I do not know how switch/fallback
> between versions occur during normal browsing.
> I recovered access to the URL, but following your explanation the 502
> were due to the temporary apache setup.
> - I know little about Apache and especially RPAF module, but Googling a
> little around I found that:
> I do not know if that would help, but who knows? If you are using
> Debian, it seems there was an update at the end of January.

I saw that and others like it. Not using Debian but I suspect that RPAF 
is the culprit. I could test it, but then I have to scour the logs to 
find the IP's of spammers and the like. They'd all show up as

I could simply have Igor delete the AAAA record and that would solve the 
problem for people with dual IPv4/IPv6 connectivity, but I'm not excited 
to do that. I've been serving the forum on IPv6 for years. It is, 
however an option, at least for now.

> - For PHP stopping accepting requests, since it is not crashing and you
> confirm the traffic volume is high, I would bet on the exhaustion of
> threads being able to accept new requests. Looks like the usual symptoms.
> Ironically, I found some answers on the Nginx ML archive that would help
> improving threads pool and PHP jobs execution time limit:

That's not the case. Not even close to out of resources. The FPM 
children are there, they're "listening", they're just not "hearing".

Jim Ohlstein

"Never argue with a fool, onlookers may not be able to tell the 
difference." - Mark Twain

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