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From Graham Leggett <minf...@sharp.fm>
Subject Re: create a pool associated with the MPM generation?
Date Mon, 22 Nov 2010 17:26:23 GMT
On 22 Nov 2010, at 2:45 PM, Jeff Trawick wrote:

> The purpose of the pool would be the allocation in the parent of
> resources which must live as long as any child processes from a
> certain generation are still running.  It helps bridge the gap between
> pconf and the process pool when dealing with graceful restart.
>
> Each MPM would be responsible for destroying the pool once the last
> child of the corresponding generation has exited.  Since graceful
> restart can be invoked again before all the children of older
> generations have exited, there could be an arbitrary number of
> generation pools at a given time.
>
> It might not be trivial to implement, but it would be a huge help for
> modules faced with this issue; it is not practical for modules to try
> to solve this lifetime issue.
>
> main() owns the generation ("for (;;) {") and would create the pool.
> The natural place to access the pool would be an additional parameter
> to hooks which take pconf currently, but that would be disruptive to
> almost every module.   The mpm hook (implemented by modules which must
> be modified anyway) would take a pointer to pgeneration, and an API
> call would be provided for other modules to use; the API would only
> support access of the current pgeneration; only the MPM would know
> about the pool for earlier generations.  Each instance of the pool
> would be a child of the process pool, created by main(), and destroyed
> by the MPM at some arbitrary point later.
>
> Problem worth solving?
> Simpler solution available?

I'd say definitely a problem worth solving, if only for the  
elimination of nasty edge cases. The solution sounds sensible.

Regards,
Graham
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