[Tile-serving] mod_tile causes segfault on debian 7.0

Tom Hughes tom at compton.nu
Wed May 22 11:49:41 UTC 2013

On 22/05/13 12:34, Andy Allan wrote:

> On 22 May 2013 12:06, Sven Geggus <lists at fuchsschwanzdomain.de> wrote:
>> I get segmentation faults in mod_tile on a more or less regular basis which
>> will leave apache in a 100% CPU on all cores state!
> Ah, that's interesting, I'm seeing something very similar. I'm using
> 1341e129e5 (22 April) with apache2-mpm-event 2.2.22 (on Ubuntu 12.04)
> I'm not sure that commit is necessarily involved, since it doesn't
> change anything for apache 2.2, but perhaps the bug was introduced
> elsewhere and that commit is just a symptom? I'm just using renderd
> with a normal disk backend, if that helps.

The point is that before the pluggable storage backends were added that 
code didn't exist at all.

Once they were added the use of the process pool in a function that 
might be called in multiple threads at once was not robust, so that 
commit was added to make things robust.

Unfortunately there is no way (that Kai has found) to get a per-thread 
memory pool on 2.2 so the old code is still used there, which will quite 
likely crash if you are using a threaded mpm.


Tom Hughes (tom at compton.nu)

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