nginx crashing w/ core dump under moderate load

[Maxim Dounin]

Hello!

On Sat, Nov 20, 2010 at 09:26:07AM -0500, Whirlycott wrote:

> It turns out that removing the "max_size=1000m inactive=1m" 
> attributes for the proxy_cache_path directive removes the 
> constant core-dumping crashiness that we have been experiencing.
> 
> Any thoughts as to why this may be the case would be 
> interesting.

Looks like insufficient locking and inactive=1m is low enough to 
trigger problems between cache manager removing entries from cache 
and nginx workers updating it.

You may want to check which atomic ops are used in your setup.  In 
particular, 

> >> built by gcc 4.1.2 20080704 (Red Hat 4.1.2-48)

gcc you used to complile nginx looks somewhat old, though it 
have builtin atomic ops.  If there are bugs in them - you'll 
likely to see similar segfaults (and AFAIR there were problems on 
modern CPUs...).

Trivial test is to try recompiling nginx with something like

./configure --with-cc-opt="-DNGX_HAVE_GCC_ATOMIC=0"

and check if it helps.

Maxim Dounin