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From Greg Ames <grega...@remulak.net>
Subject Re: [PATCH] threaded MPM: limit re-use of scoreboard
Date Sat, 28 Jul 2001 00:52:39 GMT
Greg Ames wrote:
> 
> This patch prevents multiple processes which are starting up from
> grabbing the same process slot in the scoreboard.  Other processes may
> still share that process slot while they are quiescing (due to
> MaxRequestsPerChild, perform_idle_server_maintenance, or restarts).
> 
> Since only one process per slot will be starting new threads at any
> given time, it eliminates the race conditions where multiple processes
> both see what looks like a vacant worker slot simultaneously.
> 
> This works for me.  I would appreciate comments, and would love to see
> other folks bang on it.

whoops...there's a bug with the patch I posted earlier.  If multiple
threads from a dying process are allowed to set "quiescing", then under
worst case conditions, the same number of new processes are allowed to
use the same process slot in the scoreboard.  The fix is that only the
first thread that exits is allowed to set "quiescing".

Please use this patch instead.

Greg
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