Bug #67181 [Com]: Event port code needs to reassociate to port after an event

From: Date: Tue, 08 Jul 2014 14:47:05 +0000
Subject: Bug #67181 [Com]: Event port code needs to reassociate to port after an event
References: 1  Groups: php.bugs 
Request: Send a blank email to php-bugs+get-186529@lists.php.net to get a copy of this message 
Edit report at https://bugs.php.net/bug.php?id=67181&edit=1

 ID:                 67181
 Comment by:         d dot v dot taylor at leedsmet dot ac dot uk
 Reported by:        d dot v dot taylor at leedsmet dot ac dot uk
 Summary:            Event port code needs to reassociate to port after
                     an event
 Status:             Open
 Type:               Bug
 Package:            FPM related
 Operating System:   Solaris 11.1
 PHP Version:        5.5.12
 Block user comment: N
 Private report:     N

 New Comment:

From a quick read, the patch attached to bug #65800 puts this re-association in.


Previous Comments:
------------------------------------------------------------------------
[2014-05-02 15:34:38] d dot v dot taylor at leedsmet dot ac dot uk

Description:
------------
I've enabled request_slowlog_timeout on PHP-FPM, but it only seems to successfully act on the
first request. Subsequent slow requests cause child processes to be sent the SIGSTOP but they
*don't* then get traced and SIGCONT-ed, leaving them in a stopped state indefinitely.

I've investigated this and it looks like the problem is connected to the port event module.
This is a section of the port_associate man page:

     When an event for a PORT_SOURCE_FD object is retrieved,  the
     object  no  longer  has  an  association with the port.  The
     event can be processed without the possibility that  another
     thread  can retrieve a subsequent event for the same object.
     After processing of the file descriptor  is  completed,  the
     port_associate()  function  can be called to reassociate the
     object with the port.

i.e. if any events are successfully read from the port in fpm_event_port_wait(), it needs an
explicit call to port_associate() again to re-establish the association and ensure future events are
listened for.

At the moment this doesn't happen, and so the parent FPM process doesn't see the
subsequent port events caused by child processes being stopped.

The problem doesn't occur if I switch to using /dev/poll for the event mechanism.

Test script:
---------------
<?php
    /* Set e.g. request_slowlog_timeout = 5 */
    sleep(10);
    phpinfo();
?>



------------------------------------------------------------------------



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