From nobody@hyperreal.com  Thu Apr 24 03:50:41 1997
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Date: Thu, 24 Apr 1997 03:50:41 -0700 (PDT)
From: Dean Gaudet <dgaudet@apache.org>
Reply-To: dgaudet@apache.org
To: apbugs@hyperreal.com
Subject: possible starved listening sockets -- httpd stops responding
X-Send-Pr-Version: 3.2

>Number:         467
>Category:       config
>Synopsis:       possible starved listening sockets -- httpd stops responding
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    apache
>State:          closed
>Class:          sw-bug
>Submitter-Id:   apache
>Arrival-Date:   Thu Apr 24 04:00:01 1997
>Last-Modified:  Mon Oct 27 11:39:45 PST 1997
>Originator:     dgaudet@apache.org
>Organization:
>Release:        1.2
>Environment:
All that do not USE_xxxxx_SERIALIZED_ACCEPT.
>Description:
It is possible on architectures that do not USE_xxxxx_SERIALIZED_ACCEPT
to freeze out some listening sockets when multiple Listen directives
are used.  The workaround is to add -DUSE_FLOCK_SERIALIZED_ACCEPT to
the EXTRA_CFLAGS line in the Configuration file.

See src/conf.h to determine if your architecture is affected.  This affects
many architectures.
>How-To-Repeat:

>Fix:
The permanent fix will likely involve using non-blocking listening sockets.
But experimentation is needed to determine if it's faster to serialize
accept()s than it is to deal with potentially many EAGAIN/EWOULDBLOCKs
>Audit-Trail:

From: Dean Gaudet <dgaudet@apache.org>
To: apbugs@apache.org
Subject: Re: config/467: possible starved listening sockets -- httpd stops responding
Date: Thu, 24 Apr 1997 04:02:16 -0700 (PDT)

 
 Addendum:  If you have problems using -DUSE_FLOCK_SERIALIZED_ACCEPT then
 you can also try -DUSE_FCNTL_SERIALIZED_ACCEPT.
 
 Dean
 

From: Dean Gaudet <dgaudet@apache.org>
To: apbugs@apache.org
Subject: Re: config/467: possible starved listening sockets -- httpd stops responding
Date: Fri, 2 May 1997 15:43:26 -0700 (PDT)

 
 Another addendum:  the current code requires you to have a /usr/tmp
 directory (it can be a symlink to one of your other tmp directories).
 
 Dean
 
 
Comment-Added-By: dgaudet
Comment-Added-When: Sat Jun 28 13:50:43 PDT 1997
Comment-Added:
Note that other symptoms that can indicate a need to use a
serialized accept include periodic load spikes.  We are
considering using serialized accept on more architectures
in 1.2.1.
State-Changed-From-To: open-feedback
State-Changed-By: coar
State-Changed-When: Tue Oct 21 07:49:33 PDT 1997
State-Changed-Why:
Has this been resolved by 1.3b2?

From: Dean Gaudet <dgaudet@arctic.org>
To: coar@hyperreal.org
Cc: apbugs@apache.org
Subject: Re: config/467: possible starved listening sockets -- httpd stops responding
Date: Tue, 21 Oct 1997 10:52:12 -0700 (PDT)

 No, it's not resolved until every host has serialized accept, or we put in
 a test for those without serialized accept... something like this: 
 
 #if !defined(USE_xxx_SERIALIZED_ACCEPT) && !defined(USE_yyy_SERIA...
     if (listeners->next != listeners) {
 	aplog_error(APLOG_MARK, APLOG_NOERRNO|APLOG_CRIT,
 	    "you cannot use multiple sockets safely on your system,"
 	    " proceeding anyway");
     }
 #endif
 
 Dean
 
State-Changed-From-To: feedback-closed
State-Changed-By: dgaudet
State-Changed-When: Mon Oct 27 11:39:44 PST 1997
State-Changed-Why:
As of 1.3b3 Apache will warn when this bug may manifest itself.
The user then can either work around it by using only single
Listens, or by supplying the appropriate serialization directive
as documented in src/PORTING.

Dean
>Unformatted: