On Wed, 23 Feb 2022, Stefan Eissing wrote:
On 2/23/22 11:39 AM, Stefan Eissing wrote:
One thing that is currently missing is a way to shutdown/reap/join module
threads when the mpm exits.
Example:
mod_watchdog creates several threads post_config which are only joined on pool
destruction.
Problem:
pool destruction is not ordered between modules and dependencies on order are
not
fully known. This leads to crashes in OpenSSL, for example, when mod_ssl is
destructed
before all watchdogs using OpenSSL are joined (OpenSSL 3.x seems to do better
on this,
but the point remains valid).
There has been attempts by Yann to make a patch that make the OpenSSL
termination
way later (adding it to a 'higher' pool destruction). But that would only solve
this particular problem and not any other 3rd party dependency.
Proposal:
Add a hook 'child_exiting(int graceful)' where modules can register
and do their own thread join/reap.
How does that differ from the child_stopping hook? Or is child_stopping only
used when we shutdown the whole httpd not just one child?
child_is_stopping is called when the shutdown is initiated.
child_is_exiting would be called before pool destruction begins.
The difference is that between those two, ongoing requests are still being
served on graceful shutdowns.
FWIW, I'm +1 to the idea. The current situation is no fun for our
home-grown cache module (ie it has threads that crashes on pool
destruction now and then).
Opening the bike shed: child_has_stopped?
Neither name is fully self-explanatory, I'd need to look at the
descriptive function header to figure out when to use it. However, I
don't know if a name such as child_pre_pooldestroy or somesuch would
be any better...
As long as it's not elvis_leaving_building I'm happy ;)
/Nikke
--
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Niklas Edmundsson, Admin @ {acc,hpc2n}.umu.se | ni...@acc.umu.se
---------------------------------------------------------------------------
Gene Roddenberry showed us the future...Make It So!
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
