Apache Reload Crash with slotmem-shm

[R]

Description: Ubuntu 18.04 LTS
Release: 18.04

 *** 2.4.29-1ubuntu4.1 500
        500 http://security.ubuntu.com/ubuntu bionic-security/main amd64 Packages
        100 /var/lib/dpkg/status
When i reload apache

[Tue Jul 24 16:17:26.783249 2018] [slotmem_shm:error] [pid 23188:tid 139792764550080] (28)No space left on device: AH02611: create: apr_shm_create(/var/run/apache2/slotmem-shm-p1f70c100_XXXX.shm) failed
[Tue Jul 24 16:17:26.783287 2018] [proxy_balancer:emerg] [pid 23188:tid 139792764550080] (28)No space left on device: AH01185: worker slotmem_create failed
[Tue Jul 24 16:17:26.783293 2018] [:emerg] [pid 23188:tid 139792764550080] AH00020: Configuration Failed, exiting

Apache Revision 1834887

mod_slotmem_shm: use a generation number for SHM filename on all platforms.

Successive generations can't share the same SHMs because restarts may modify
them under the terminating children, while SHMs are not extensible when all
slots are in use.

[Andreas Hasenack (ahasenack)]

Possibly same bug reported in Debian: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=896090

[Andreas Hasenack (ahasenack)]

Would you be able to share the config for a reproducer of this bug? I suppose you have a lot of proxy balancers, and/or vhosts?

[R (gregory.r)]

Sorry, it's production so it's not be possible.
Yes, 31 proxy balancer and 200 vhosts
We have to do a restart for each modification, and modify the logrotate (replace the reload by restart) to avoid the crash each morning.

[Andreas Hasenack (ahasenack)]

It could be https://bz.apache.org/bugzilla/show_bug.cgi?id=62044. That patch (https://bz.apache.org/bugzilla/attachment.cgi?id=35723) is quite big (~30kbytes), but applies cleanly to the bionic package.

[R (gregory.r)]

I compiled the version with
apache2_2.4.29.orig.tar.gz,patch of apache2_2.4.29-1ubuntu4.2.debian.tar.xz and the patch of
https://bz.apache.org/bugzilla/attachment.cgi?id=35723

And I put mod_proxy_balancer.so, mod_slotmem_shm.so on a clone of the production VM.

But it doesn't work,i have error messages when i reload:

Directory /var/run/apache2 is empty

Start :
[Thu Aug 07 09:40:53.271008 2018] [ slotmem_shm:error] [pid 25187: tid 140664450165696] AH02599: exiting shared memory for /var/run/apache2/slotmem-shm-pf6557ba_XXXXX.shm could not be used (failed size check)
...

but Directory /var/run/apache2/ is no empty

Reload:
[Thu Aug 07 09:46:22.930184 2018] [ proxy_balancer:emerg] [pid 25187: tid 140664450165696] (22)invalid argument: AH01186: worker slotmem_grab failed
...
[Thu Aug 07 09:46:23.067853 2018] [:emerg] [pid 25187: tid 140664450165696] AH00020: Configuration Failed, exiting

Thank