Lucas and I have re-visited the Zend Signal Handling RFC and have updated the patches for both the 5.3 branch and Trunk:
http://wiki.php.net/rfc/zendsignals
We updated the patches to deal with a bug fix that allows timeouts within the user space shutdown functions, previously multiple timeouts would not occur. To deal with this we reset the signal handlers on a timeout so that the user shutdown function can once again get a signal and behave accordingly.
Per the Chicago developer meeting, it was determined that the windows timeouts are not asynchronous and thus there isn't currently any special handling required for critical sections on the windows builds.
We would like to hear about any other issues/feedback with this patch, and if there's no objections get this checked in as it will assist with getting more stability for signal handling (specific example is the use of spin-locks with APC).
Thanks!,
-shire