Hello!

On Wed, Apr 18, 2012 at 01:06:25AM -0400, mscheel wrote:

> Hello Maxim,
>
> it appears only on two productive servers. Compiling without these
> modules is not possible at the moment but i've tried several times with
> each module deactivated (and without any of these three).
>
> Full config is huge. I'm using a php-fpm backend with keepalive on and
> one upstream server with nginx and php-fpm.

[...]

> upstream be_server_nginx {
> server IP:80;
> keepalive 300;
> }
> }
>
> ...
>
> location @be_nginx {
> proxy_pass http://be_server_nginx;
> proxy_set_header Connection ""; proxy_http_version 1.1;
> include /etc/nginx/proxy.conf;

This part of the config shows proxy_pass, while gdb prints
provided say the request used fastcgi_pass. Could you please:

1. Check processing flow of the
"/nc/pdf-generation.html?pageID=776404" uri and provide relevant
parts of the config. According to gdb it's transformed to
"/index.php?pageID=776404".

2. Check if the problem is reproduceable with the uri in question.

3. Check if the problem persists with the upstream keepalive
turned off.

It would be also cool to obtain debug log if possible, it should
be ok to grab one from a particular location with fastcgi_pass.

And see below from more gdb commands I would like to see output
from.

> output of gdb:
>
> (gdb) fr 0
> #0 0x000000000042cbe8 in ngx_readv_chain (c=0x2b508a1d43d0,
> chain=0x602348) at src/os/unix/ngx_readv_chain.c:195
> 195 in src/os/unix/ngx_readv_chain.c
>
> (gdb) p chain
> $1 = (ngx_chain_t *) 0x602348
>
> (gdb) p *chain
> $2 = {buf = 0x602460, next = 0x752628}

fr 0
p *chain->buf
p *chain->next
p *chain->next->buf
p *chain->next->next
p *chain->next->next->buf

(repeat last two prints with one more "->next" added till it fails)

> (gdb) fr 1
> #1 0x000000000042b133 in ngx_event_pipe (p=0x747170, do_write=<value
> optimized out>) at src/event/ngx_event_pipe.c:271
> 271 src/event/ngx_event_pipe.c: No such file or directory.
> in src/event/ngx_event_pipe.c
>
> (gdb) p *p
> $3 = {upstream = 0x2b508a1d43d0, downstream = 0x2b508a1d4550,
> free_raw_bufs = 0x0, in = 0x6024d0, last_in = 0x7523a0, out = 0x0, free
> = 0x602450, busy = 0x0,

fr 1
p *p->in
p *p->in->buf
p *p->in->next
p *p->in->next->buf

(same here, repeat with "->next" added till it fails)

p *p->free
p *p->free->buf
p *p->free->next
p *p->free->next->buf

(same here)

[...]

Maxim Dounin

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